KnowledgeBoat Logo
|
OPEN IN APP

Chapter 3

Fractions — Exercise 3(C)

Class - 7 Concise Mathematics Selina



Exercise 3(C)

Question 1(i)

Reduce to a single fraction:

12+23\dfrac{1}{2} + \dfrac{2}{3}

Answer

LCM of 2 and 3 = 6.

Solving,

12+23=1×36+2×26=3+46=76=116\Rightarrow \dfrac{1}{2} + \dfrac{2}{3} \\[1em] = \dfrac{1 \times 3}{6} + \dfrac{2 \times 2}{6} \\[1em] = \dfrac{3 + 4}{6} = \dfrac{7}{6} \\[1em] = 1\dfrac{1}{6}

Hence, the required fraction is 1161\dfrac{1}{6}.

Question 1(ii)

Reduce to a single fraction:

35110\dfrac{3}{5} - \dfrac{1}{10}

Answer

LCM of 5 and 10 = 10.

35110=3×210110=6110=510=12\Rightarrow \dfrac{3}{5} - \dfrac{1}{10} = \dfrac{3 \times 2}{10} - \dfrac{1}{10}\\[1em] = \dfrac{6 - 1}{10} = \dfrac{5}{10}\\[1em] = \dfrac{1}{2}

Hence, the required fraction is 12\dfrac{1}{2}.

Question 1(iii)

Reduce to a single fraction:

2316\dfrac{2}{3} - \dfrac{1}{6}

Answer

LCM of 3 and 6 = 6.

2316=2×2616=416=36=12\Rightarrow \dfrac{2}{3} - \dfrac{1}{6} = \dfrac{2 \times 2}{6} - \dfrac{1}{6}\\[1em] = \dfrac{4 - 1}{6} = \dfrac{3}{6}\\[1em] = \dfrac{1}{2}

Hence, the required fraction is 12\dfrac{1}{2}.

Question 1(iv)

Reduce to a single fraction:

113+2141\dfrac{1}{3} + 2\dfrac{1}{4}

Answer

113+214=43+941\dfrac{1}{3} + 2\dfrac{1}{4} = \dfrac{4}{3} + \dfrac{9}{4}

LCM of 3 and 4 = 12.

=4×412+9×312=16+2712=4312=3712= \dfrac{4 \times 4}{12} + \dfrac{9 \times 3}{12}\\[1em] = \dfrac{16 + 27}{12} \\[1em] = \dfrac{43}{12}\\[1em] = 3\dfrac{7}{12}

Hence, the required fraction is 37123\dfrac{7}{12}.

Question 1(v)

Reduce to a single fraction:

14+56112\dfrac{1}{4} + \dfrac{5}{6} - \dfrac{1}{12}

Answer

LCM of 4, 6 and 12 = 12.

14+56112=1×312+5×212112=3+10112=1212=1\Rightarrow \dfrac{1}{4} + \dfrac{5}{6} - \dfrac{1}{12}\\[1em] = \dfrac{1 \times 3}{12} + \dfrac{5 \times 2}{12} - \dfrac{1}{12} \\[1em] = \dfrac{3 + 10 - 1}{12} \\[1em] = \dfrac{12}{12} = 1

Hence, the required fraction is 1.

Question 1(vi)

Reduce to a single fraction:

2335+315\dfrac{2}{3} - \dfrac{3}{5} + 3 - \dfrac{1}{5}

Answer

LCM of 1, 3 and 5 = 15.

2335+315=2×5153×315+3×15151×315=109+45315=4315=21315\Rightarrow \dfrac{2}{3} - \dfrac{3}{5} + 3 - \dfrac{1}{5} \\[1em] = \dfrac{2 \times 5}{15} - \dfrac{3 \times 3}{15} + \dfrac{3 \times 15}{15} - \dfrac{1 \times 3}{15} \\[1em] = \dfrac{10 - 9 + 45 - 3}{15} = \dfrac{43}{15} = 2\dfrac{13}{15}

Hence, the required fraction is 213152\dfrac{13}{15}.

Question 1(vii)

Reduce to a single fraction:

2315+110\dfrac{2}{3} - \dfrac{1}{5} + \dfrac{1}{10}

Answer

LCM of 3, 5 and 10 = 30.

2315+110=2×10301×630+1×330=206+330=1730\Rightarrow \dfrac{2}{3} - \dfrac{1}{5} + \dfrac{1}{10}\\[1em] = \dfrac{2 \times 10}{30} - \dfrac{1 \times 6}{30} + \dfrac{1 \times 3}{30} \\[1em] = \dfrac{20 - 6 + 3}{30} \\[1em] = \dfrac{17}{30}

Hence, the required fraction is 1730\dfrac{17}{30}.

Question 1(viii)

Reduce to a single fraction:

212+2131142\dfrac{1}{2} + 2\dfrac{1}{3} - 1\dfrac{1}{4}

Answer

212+213114=52+73542\dfrac{1}{2} + 2\dfrac{1}{3} - 1\dfrac{1}{4} = \dfrac{5}{2} + \dfrac{7}{3} - \dfrac{5}{4}

LCM of 2, 3 and 4 = 12.

=5×612+7×4125×312=30+281512=4312=3712= \dfrac{5 \times 6}{12} + \dfrac{7 \times 4}{12} - \dfrac{5 \times 3}{12} \\[1em] = \dfrac{30 + 28 - 15}{12} \\[1em] = \dfrac{43}{12}\\[1em] = 3\dfrac{7}{12}

Hence, the required fraction is 37123\dfrac{7}{12}.

Question 1(ix)

Reduce to a single fraction:

258216+4342\dfrac{5}{8} - 2\dfrac{1}{6} + 4\dfrac{3}{4}

Answer

258216+434=218136+1942\dfrac{5}{8} - 2\dfrac{1}{6} + 4\dfrac{3}{4} = \dfrac{21}{8} - \dfrac{13}{6} + \dfrac{19}{4}

LCM of 8, 6 and 4 = 24.

=21×32413×424+19×624=6352+11424=12524=5524= \dfrac{21 \times 3}{24} - \dfrac{13 \times 4}{24} + \dfrac{19 \times 6}{24} \\[1em] = \dfrac{63 - 52 + 114}{24} = \dfrac{125}{24} = 5\dfrac{5}{24}

Hence, the required fraction is 55245\dfrac{5}{24}.

Question 2(i)

Simplify:

34×6\dfrac{3}{4} \times 6

Answer

Solving,

34×6=3×64=184=92=412\Rightarrow \dfrac{3}{4} \times 6 \\[1em] = \dfrac{3 \times 6}{4} \\[1em] = \dfrac{18}{4} \\[1em] = \dfrac{9}{2} \\[1em] = 4\dfrac{1}{2}

Hence, the required value is 4124\dfrac{1}{2}.

Question 2(ii)

Simplify:

23×15\dfrac{2}{3} \times 15

Answer

Solving,

23×15=2×153=303=10\Rightarrow \dfrac{2}{3} \times 15 \\[1em] = \dfrac{2 \times 15}{3} \\[1em] = \dfrac{30}{3} \\[1em] = 10

Hence, the required value is 10.

Question 2(iii)

Simplify:

34×12\dfrac{3}{4} \times \dfrac{1}{2}

Answer

Solving,

34×12=3×14×2=38\Rightarrow \dfrac{3}{4} \times \dfrac{1}{2} \\[1em] = \dfrac{3 \times 1}{4 \times 2} \\[1em] = \dfrac{3}{8}

Hence, the required value is 38\dfrac{3}{8}.

Question 2(iv)

Simplify:

912×47\dfrac{9}{12} \times \dfrac{4}{7}

Answer

Solving,

912×47=9×412×7=3684=37\Rightarrow \dfrac{9}{12} \times \dfrac{4}{7} \\[1em] = \dfrac{9 \times 4}{12 \times 7} \\[1em] = \dfrac{36}{84} \\[1em] = \dfrac{3}{7}

Hence, the required value is 37\dfrac{3}{7}.

Question 2(v)

Simplify:

45×21345 \times 2\dfrac{1}{3}

Answer

Solving,

45×213=45×73=45×73=3153=105\Rightarrow 45 \times 2\dfrac{1}{3} \\[1em] = 45 \times \dfrac{7}{3} \\[1em] = \dfrac{45 \times 7}{3} \\[1em] = \dfrac{315}{3} \\[1em] = 105

Hence, the required value is 105.

Question 2(vi)

Simplify:

36×31436 \times 3\dfrac{1}{4}

Answer

Solving,

36×314=36×134=36×134=4684=117\Rightarrow 36 \times 3\dfrac{1}{4} \\[1em] = 36 \times \dfrac{13}{4} \\[1em] = \dfrac{36 \times 13}{4} \\[1em] = \dfrac{468}{4} \\[1em] = 117

Hence, the required value is 117.

Question 2(vii)

Simplify:

2÷132 \div \dfrac{1}{3}

Answer

Solving,

2÷13=2×31=6\Rightarrow 2 \div \dfrac{1}{3} \\[1em] = 2 \times \dfrac{3}{1} \\[1em] = 6

Hence, the required value is 6.

Question 2(viii)

Simplify:

3÷253 \div \dfrac{2}{5}

Answer

Solving,

3÷25=3×52=152=712\Rightarrow 3 \div \dfrac{2}{5} \\[1em] = 3 \times \dfrac{5}{2} \\[1em] = \dfrac{15}{2} \\[1em] = 7\dfrac{1}{2}

Hence, the required value is 7127\dfrac{1}{2}.

Question 2(ix)

Simplify:

1÷351 \div \dfrac{3}{5}

Answer

Solving,

1÷35=1×53=53=123\Rightarrow 1 \div \dfrac{3}{5} \\[1em] = 1 \times \dfrac{5}{3} \\[1em] = \dfrac{5}{3} \\[1em] = 1\dfrac{2}{3}

Hence, the required value is 1231\dfrac{2}{3}.

Question 2(x)

Simplify:

13÷14\dfrac{1}{3} \div \dfrac{1}{4}

Answer

Solving,

13÷14=13×41=43=113\Rightarrow \dfrac{1}{3} \div \dfrac{1}{4} \\[1em] = \dfrac{1}{3} \times \dfrac{4}{1} \\[1em] = \dfrac{4}{3} \\[1em] = 1\dfrac{1}{3}

Hence, the required value is 1131\dfrac{1}{3}.

Question 2(xi)

Simplify:

58÷34-\dfrac{5}{8} \div \dfrac{3}{4}

Answer

Solving,

58÷34=58×43=5×48×3=2024=56\Rightarrow -\dfrac{5}{8} \div \dfrac{3}{4} \\[1em] = -\dfrac{5}{8} \times \dfrac{4}{3} \\[1em] = -\dfrac{5 \times 4}{8 \times 3} \\[1em] = -\dfrac{20}{24} \\[1em] = -\dfrac{5}{6}

Hence, the required value is 56-\dfrac{5}{6}.

Question 2(xii)

Simplify:

337÷11143\dfrac{3}{7} \div 1\dfrac{1}{14}

Answer

Solving,

337÷1114=247÷1514=247×1415=24×147×15=336105=165=315\Rightarrow 3\dfrac{3}{7} \div 1\dfrac{1}{14} \\[1em] = \dfrac{24}{7} \div \dfrac{15}{14} \\[1em] = \dfrac{24}{7} \times \dfrac{14}{15} \\[1em] = \dfrac{24 \times 14}{7 \times 15} \\[1em] = \dfrac{336}{105} \\[1em] = \dfrac{16}{5} \\[1em] = 3\dfrac{1}{5}

Hence, the required value is 3153\dfrac{1}{5}.

Question 2(xiii)

Simplify:

334×115×20213\dfrac{3}{4} \times 1\dfrac{1}{5} \times \dfrac{20}{21}

Answer

Solving,

334×115×2021=154×65×2021=15×6×204×5×21=1800420=307=427\Rightarrow 3\dfrac{3}{4} \times 1\dfrac{1}{5} \times \dfrac{20}{21} \\[1em] = \dfrac{15}{4} \times \dfrac{6}{5} \times \dfrac{20}{21} \\[1em] = \dfrac{15 \times 6 \times 20}{4 \times 5 \times 21} \\[1em] = \dfrac{1800}{420} \\[1em] = \dfrac{30}{7} \\[1em] = 4\dfrac{2}{7}

Hence, the required value is 4274\dfrac{2}{7}.

Question 3(i)

Subtract:

2 from 23\dfrac{2}{3}

Answer

Solving,

232236326343113\Rightarrow \dfrac{2}{3} - 2 \\[1em] \Rightarrow \dfrac{2}{3} - \dfrac{6}{3} \\[1em] \Rightarrow \dfrac{2 - 6}{3} \\[1em] \Rightarrow -\dfrac{4}{3} \\[1em] \Rightarrow -1\dfrac{1}{3}

Hence, the required value is 113-1\dfrac{1}{3}.

Question 3(ii)

Subtract:

18 from 58\dfrac{1}{8} \text{ from } \dfrac{5}{8}

Answer

Solving,

5818=518=48=12\dfrac{5}{8} - \dfrac{1}{8} = \dfrac{5 - 1}{8} \\[1em] = \dfrac{4}{8} = \dfrac{1}{2}

Hence, the required value is 12\dfrac{1}{2}.

Question 3(iii)

Subtract:

25 from 25-\dfrac{2}{5} \text{ from } \dfrac{2}{5}

Answer

Solving,

25(25)=25+25=2+25=45\dfrac{2}{5} - \left(-\dfrac{2}{5}\right) = \dfrac{2}{5} + \dfrac{2}{5} \\[1em] = \dfrac{2 + 2}{5} = \dfrac{4}{5}

Hence, the required value is 45\dfrac{4}{5}.

Question 3(iv)

Subtract:

37 from 37-\dfrac{3}{7} \text{ from } \dfrac{3}{7}

Answer

Solving,

37(37)=37+37=3+37=67\dfrac{3}{7} - \left(-\dfrac{3}{7}\right) = \dfrac{3}{7} + \dfrac{3}{7} \\[1em] = \dfrac{3 + 3}{7} = \dfrac{6}{7}

Hence, the required value is 67\dfrac{6}{7}.

Question 3(v)

Subtract:

0 from 45-\dfrac{4}{5}

Answer

Solving,

450=45-\dfrac{4}{5} - 0 = -\dfrac{4}{5}

Hence, the required value is 45-\dfrac{4}{5}.

Question 3(vi)

Subtract:

29 from 45\dfrac{2}{9} \text{ from } \dfrac{4}{5}

Answer

4529\dfrac{4}{5} - \dfrac{2}{9}

LCM of 5 and 9 = 45.

=4×9452×545=361045=2645= \dfrac{4 \times 9}{45} - \dfrac{2 \times 5}{45} \\[1em] = \dfrac{36 - 10}{45} = \dfrac{26}{45}

Hence, the required value is 2645\dfrac{26}{45}.

Question 3(vii)

Subtract:

47 from 611-\dfrac{4}{7} \text{ from } -\dfrac{6}{11}

Answer

611(47)=611+47-\dfrac{6}{11} - \left(-\dfrac{4}{7}\right) = -\dfrac{6}{11} + \dfrac{4}{7}

LCM of 11 and 7 = 77.

=6×777+4×1177=42+4477=277= -\dfrac{6 \times 7}{77} + \dfrac{4 \times 11}{77} \\[1em] = \dfrac{-42 + 44}{77} = \dfrac{2}{77}

Hence, the required value is 277\dfrac{2}{77}.

Question 4(i)

Find the value of:

12\dfrac{1}{2} of 10 kg

Answer

Solving,

12 of 10 kg12×105 kg\Rightarrow \dfrac{1}{2} \text{ of } 10 \text{ kg} \\[1em] \Rightarrow \dfrac{1}{2} \times 10 \\[1em] \Rightarrow 5 \text{ kg}

Hence, the required value is 5 kg.

Question 4(ii)

Find the value of:

35\dfrac{3}{5} of 1 hour

Answer

1 hour = 60 minutes.

Solving,

35 of 1 hour35×6036 minutes\Rightarrow \dfrac{3}{5} \text{ of } 1 \text{ hour} \\[1em] \Rightarrow \dfrac{3}{5} \times 60 \\[1em] \Rightarrow 36 \text{ minutes}

Hence, the required value is 36 minutes.

Question 4(iii)

Find the value of:

47 of 213\dfrac{4}{7} \text{ of } 2\dfrac{1}{3} kg

Answer

Solving,

47 of 213 kg47×734×77×343113 kg\Rightarrow \dfrac{4}{7} \text{ of } 2\dfrac{1}{3} \text{ kg} \\[1em] \Rightarrow \dfrac{4}{7} \times \dfrac{7}{3} \\[1em] \Rightarrow \dfrac{4 \times 7}{7 \times 3} \\[1em] \Rightarrow \dfrac{4}{3} \\[1em] \Rightarrow 1\dfrac{1}{3} \text{ kg}

Hence, the required value is 1131\dfrac{1}{3} kg.

Question 4(iv)

Find the value of:

3123\dfrac{1}{2} times of 2 metre

Answer

Solving,

312 times of 2 metre72×27 metres\Rightarrow 3\dfrac{1}{2} \text{ times of } 2 \text{ metre} \\[1em] \Rightarrow \dfrac{7}{2} \times 2 \\[1em] \Rightarrow 7 \text{ metres}

Hence, the required value is 7 metres.

Question 4(v)

Find the value of:

12 of 223\dfrac{1}{2} \text{ of } 2\dfrac{2}{3}

Answer

Solving,

12 of 22312×838643113\Rightarrow \dfrac{1}{2} \text{ of } 2\dfrac{2}{3} \\[1em] \Rightarrow \dfrac{1}{2} \times \dfrac{8}{3} \\[1em] \Rightarrow \dfrac{8}{6} \\[1em] \Rightarrow \dfrac{4}{3} \\[1em] \Rightarrow 1\dfrac{1}{3}

Hence, the required value is 1131\dfrac{1}{3}.

Question 4(vi)

Find the value of:

511 of 45\dfrac{5}{11} \text{ of } \dfrac{4}{5} of 22 kg

Answer

Solving,

511 of 45 of 22 kg511×45×225×4×2211×5440558 kg\Rightarrow \dfrac{5}{11} \text{ of } \dfrac{4}{5} \text{ of } 22 \text{ kg} \\[1em] \Rightarrow \dfrac{5}{11} \times \dfrac{4}{5} \times 22 \\[1em] \Rightarrow \dfrac{5 \times 4 \times 22}{11 \times 5} \\[1em] \Rightarrow \dfrac{440}{55} \\[1em] \Rightarrow 8 \text{ kg}

Hence, the required value is 8 kg.

Question 5(i)

Simplify and reduce to a simple fraction:

3334\dfrac{3}{3\dfrac{3}{4}}

Answer

Solving,

33343÷1543×415121545\Rightarrow \dfrac{3}{3\dfrac{3}{4}} \\[1em] \Rightarrow 3 \div \dfrac{15}{4} \\[1em] \Rightarrow 3 \times \dfrac{4}{15} \\[1em] \Rightarrow \dfrac{12}{15} \\[1em] \Rightarrow \dfrac{4}{5}

Hence, the required value is 45\dfrac{4}{5}.

Question 5(ii)

Simplify and reduce to a simple fraction:

357\dfrac{\dfrac{3}{5}}{7}

Answer

Solving,

35735÷735×17335\Rightarrow \dfrac{\dfrac{3}{5}}{7} \\[1em] \Rightarrow \dfrac{3}{5} \div 7 \\[1em] \Rightarrow \dfrac{3}{5} \times \dfrac{1}{7} \\[1em] \Rightarrow \dfrac{3}{35}

Hence, the required value is 335\dfrac{3}{35}.

Question 5(iii)

Simplify and reduce to a simple fraction:

357\dfrac{3}{\dfrac{5}{7}}

Answer

Solving,

3573÷573×75215415\Rightarrow \dfrac{3}{\dfrac{5}{7}} \\[1em] \Rightarrow 3 \div \dfrac{5}{7} \\[1em] \Rightarrow 3 \times \dfrac{7}{5} \\[1em] \Rightarrow \dfrac{21}{5} \\[1em] \Rightarrow 4\dfrac{1}{5}

Hence, the required value is 4154\dfrac{1}{5}.

Question 5(iv)

Simplify and reduce to a simple fraction:

2151110\dfrac{2\dfrac{1}{5}}{1\dfrac{1}{10}}

Answer

Solving,

2151110115÷1110115×1011110552\Rightarrow \dfrac{2\dfrac{1}{5}}{1\dfrac{1}{10}} \\[1em] \Rightarrow \dfrac{11}{5} \div \dfrac{11}{10} \\[1em] \Rightarrow \dfrac{11}{5} \times \dfrac{10}{11} \\[1em] \Rightarrow \dfrac{110}{55} \\[1em] \Rightarrow 2

Hence, the required value is 2.

Question 5(v)

Simplify and reduce to a simple fraction:

25 of 611×114\dfrac{2}{5} \text{ of } \dfrac{6}{11} \times 1\dfrac{1}{4}

Answer

Solving,

25 of 611×11425×611×542×6×55×11×460220311\Rightarrow \dfrac{2}{5} \text{ of } \dfrac{6}{11} \times 1\dfrac{1}{4} \\[1em] \Rightarrow \dfrac{2}{5} \times \dfrac{6}{11} \times \dfrac{5}{4} \\[1em] \Rightarrow \dfrac{2 \times 6 \times 5}{5 \times 11 \times 4} \\[1em] \Rightarrow \dfrac{60}{220} \\[1em] \Rightarrow \dfrac{3}{11}

Hence, the required value is 311\dfrac{3}{11}.

Question 5(vi)

Simplify and reduce to a simple fraction:

214÷17×132\dfrac{1}{4} \div \dfrac{1}{7} \times \dfrac{1}{3}

Answer

Solving,

214÷17×1394÷17×1394×71×139×7×14×1×36312214514\Rightarrow 2\dfrac{1}{4} \div \dfrac{1}{7} \times \dfrac{1}{3} \\[1em] \Rightarrow \dfrac{9}{4} \div \dfrac{1}{7} \times \dfrac{1}{3} \\[1em] \Rightarrow \dfrac{9}{4} \times \dfrac{7}{1} \times \dfrac{1}{3} \\[1em] \Rightarrow \dfrac{9 \times 7 \times 1}{4 \times 1 \times 3} \\[1em] \Rightarrow \dfrac{63}{12} \\[1em] \Rightarrow \dfrac{21}{4} \\[1em] \Rightarrow 5\dfrac{1}{4}

Hence, the required value is 5145\dfrac{1}{4}.

Question 5(vii)

Simplify and reduce to a simple fraction:

13×423÷312×12\dfrac{1}{3} \times 4\dfrac{2}{3} \div 3\dfrac{1}{2} \times \dfrac{1}{2}

Answer

Solving,

13×423÷312×1213×143÷72×12149×27×1214×2×19×7×22812629\Rightarrow \dfrac{1}{3} \times 4\dfrac{2}{3} \div 3\dfrac{1}{2} \times \dfrac{1}{2} \\[1em] \Rightarrow \dfrac{1}{3} \times \dfrac{14}{3} \div \dfrac{7}{2} \times \dfrac{1}{2} \\[1em] \Rightarrow \dfrac{14}{9} \times \dfrac{2}{7} \times \dfrac{1}{2} \\[1em] \Rightarrow \dfrac{14 \times 2 \times 1}{9 \times 7 \times 2} \\[1em] \Rightarrow \dfrac{28}{126} \\[1em] \Rightarrow \dfrac{2}{9}

Hence, the required value is 29\dfrac{2}{9}.

Question 5(viii)

Simplify and reduce to a simple fraction:

23×114÷37 of 258\dfrac{2}{3} \times 1\dfrac{1}{4} \div \dfrac{3}{7} \text{ of } 2\dfrac{5}{8}

Answer

Solving,

Simplifying 'of' first: 37 of 258=37×218=6356=98\dfrac{3}{7} \text{ of } 2\dfrac{5}{8} = \dfrac{3}{7} \times \dfrac{21}{8} = \dfrac{63}{56} = \dfrac{9}{8}

23×114÷37 of 25823×54÷9823×54×892×5×83×4×9801082027\Rightarrow \dfrac{2}{3} \times 1\dfrac{1}{4} \div \dfrac{3}{7} \text{ of } 2\dfrac{5}{8} \\[1em] \Rightarrow \dfrac{2}{3} \times \dfrac{5}{4} \div \dfrac{9}{8} \\[1em] \Rightarrow \dfrac{2}{3} \times \dfrac{5}{4} \times \dfrac{8}{9} \\[1em] \Rightarrow \dfrac{2 \times 5 \times 8}{3 \times 4 \times 9} \\[1em] \Rightarrow \dfrac{80}{108} \\[1em] \Rightarrow \dfrac{20}{27}

Hence, the required value is 2027\dfrac{20}{27}.

Question 5(ix)

Simplify and reduce to a simple fraction:

0÷8110 \div \dfrac{8}{11}

Answer

Solving,

0÷8110×1180\Rightarrow 0 \div \dfrac{8}{11} \\[1em] \Rightarrow 0 \times \dfrac{11}{8} \\[1em] \Rightarrow 0

Hence, the required value is 0.

Question 5(x)

Simplify and reduce to a simple fraction:

45÷715 of 89\dfrac{4}{5} \div \dfrac{7}{15} \text{ of } \dfrac{8}{9}

Answer

Solving,

Simplifying 'of' first: 715 of 89=715×89=56135\dfrac{7}{15} \text{ of } \dfrac{8}{9} = \dfrac{7}{15} \times \dfrac{8}{9} = \dfrac{56}{135}

45÷715 of 8945÷5613545×135564×1355×56540280271411314\Rightarrow \dfrac{4}{5} \div \dfrac{7}{15} \text{ of } \dfrac{8}{9} \\[1em] \Rightarrow \dfrac{4}{5} \div \dfrac{56}{135} \\[1em] \Rightarrow \dfrac{4}{5} \times \dfrac{135}{56} \\[1em] \Rightarrow \dfrac{4 \times 135}{5 \times 56} \\[1em] \Rightarrow \dfrac{540}{280} \\[1em] \Rightarrow \dfrac{27}{14} \\[1em] \Rightarrow 1\dfrac{13}{14}

Hence, the required value is 113141\dfrac{13}{14}.

Question 5(xi)

Simplify and reduce to a simple fraction:

45÷715×89\dfrac{4}{5} \div \dfrac{7}{15} \times \dfrac{8}{9}

Answer

Solving,

45÷715×8945×157×894×15×85×7×9480315322111121\Rightarrow \dfrac{4}{5} \div \dfrac{7}{15} \times \dfrac{8}{9} \\[1em] \Rightarrow \dfrac{4}{5} \times \dfrac{15}{7} \times \dfrac{8}{9} \\[1em] \Rightarrow \dfrac{4 \times 15 \times 8}{5 \times 7 \times 9} \\[1em] \Rightarrow \dfrac{480}{315} \\[1em] \Rightarrow \dfrac{32}{21} \\[1em] \Rightarrow 1\dfrac{11}{21}

Hence, the required value is 111211\dfrac{11}{21}.

Question 5(xii)

Simplify and reduce to a simple fraction:

45 of 715÷89\dfrac{4}{5} \text{ of } \dfrac{7}{15} \div \dfrac{8}{9}

Answer

Solving,

Simplifying 'of' first: 45 of 715=45×715=2875\dfrac{4}{5} \text{ of } \dfrac{7}{15} = \dfrac{4}{5} \times \dfrac{7}{15} = \dfrac{28}{75}

45 of 715÷892875÷892875×9828×975×82526002150\Rightarrow \dfrac{4}{5} \text{ of } \dfrac{7}{15} \div \dfrac{8}{9} \\[1em] \Rightarrow \dfrac{28}{75} \div \dfrac{8}{9} \\[1em] \Rightarrow \dfrac{28}{75} \times \dfrac{9}{8} \\[1em] \Rightarrow \dfrac{28 \times 9}{75 \times 8} \\[1em] \Rightarrow \dfrac{252}{600} \\[1em] \Rightarrow \dfrac{21}{50}

Hence, the required value is 2150\dfrac{21}{50}.

Question 5(xiii)

Simplify and reduce to a simple fraction:

12 of 34×12÷23\dfrac{1}{2} \text{ of } \dfrac{3}{4} \times \dfrac{1}{2} \div \dfrac{2}{3}

Answer

Solving,

Simplifying 'of' first: 12 of 34=12×34=38\dfrac{1}{2} \text{ of } \dfrac{3}{4} = \dfrac{1}{2} \times \dfrac{3}{4} = \dfrac{3}{8}

12 of 34×12÷2338×12÷23316÷23316×32932\Rightarrow \dfrac{1}{2} \text{ of } \dfrac{3}{4} \times \dfrac{1}{2} \div \dfrac{2}{3} \\[1em] \Rightarrow \dfrac{3}{8} \times \dfrac{1}{2} \div \dfrac{2}{3} \\[1em] \Rightarrow \dfrac{3}{16} \div \dfrac{2}{3} \\[1em] \Rightarrow \dfrac{3}{16} \times \dfrac{3}{2} \\[1em] \Rightarrow \dfrac{9}{32}

Hence, the required value is 932\dfrac{9}{32}.

Question 6

A bought 3343\dfrac{3}{4} kg of wheat and 2122\dfrac{1}{2} kg of rice. Find the total weight of wheat and rice bought by A.

Answer

Given,

Weight of wheat bought = 3343\dfrac{3}{4} kg

Weight of rice bought = 2122\dfrac{1}{2} kg

Total weight = Weight of wheat + Weight of rice

Total weight =334+212=154+52= 3\dfrac{3}{4} + 2\dfrac{1}{2} = \dfrac{15}{4} + \dfrac{5}{2}

LCM of 4 and 2 = 4.

=15×14×1+5×22×2=154+104=15+104=254=614 kg= \dfrac{15 \times 1}{4 \times 1} + \dfrac{5 \times 2}{2 \times 2} \\[1em] = \dfrac{15}{4} + \dfrac{10}{4} \\[1em] = \dfrac{15 + 10}{4} \\[1em] = \dfrac{25}{4} \\[1em] = 6\dfrac{1}{4} \text{ kg}

Hence, the total weight of wheat and rice is 6146\dfrac{1}{4} kg.

Question 7

Which is greater, 35 or 710\dfrac{3}{5} \text{ or } \dfrac{7}{10} and by how much?

Answer

LCM of 5 and 10 = 10.

35=3×210=610 and 710=710\dfrac{3}{5} = \dfrac{3 \times 2}{10} = \dfrac{6}{10} \text{ and } \dfrac{7}{10} = \dfrac{7}{10}

Since 7 > 6, 710>35\dfrac{7}{10} \gt \dfrac{3}{5}

Difference = 710610=110\dfrac{7}{10} - \dfrac{6}{10} = \dfrac{1}{10}

Hence, 710\dfrac{7}{10} is greater than 35 by 110\dfrac{3}{5}\text { by } \dfrac{1}{10}.

Question 8

What number should be added to 8238\dfrac{2}{3} to get 125612\dfrac{5}{6}?

Answer

Let the required number be x.

Then, 823+x=12568\dfrac{2}{3} + x = 12\dfrac{5}{6}

x=1256823=776263=77626×26=77526=256=416\Rightarrow x = 12\dfrac{5}{6} - 8\dfrac{2}{3} \\[1em] = \dfrac{77}{6} - \dfrac{26}{3} \\[1em] = \dfrac{77}{6} - \dfrac{26 \times 2}{6} \\[1em] = \dfrac{77 - 52}{6} = \dfrac{25}{6} = 4\dfrac{1}{6}

Hence, the required number is 4164\dfrac{1}{6}.

Question 9

What should be subtracted from 8348\dfrac{3}{4} to get 2232\dfrac{2}{3}?

Answer

Let the required number be x.

Then, 834x=2238\dfrac{3}{4} - x = 2\dfrac{2}{3}

x=834223=35483=35×3128×412=1053212=7312=6112\Rightarrow x = 8\dfrac{3}{4} - 2\dfrac{2}{3} \\[1em] = \dfrac{35}{4} - \dfrac{8}{3} \\[1em] = \dfrac{35 \times 3}{12} - \dfrac{8 \times 4}{12} \\[1em] = \dfrac{105 - 32}{12} = \dfrac{73}{12} = 6\dfrac{1}{12}

Hence, the required number is 61126\dfrac{1}{12}.

Question 10

A rectangular field is 161216\dfrac{1}{2} m long and 122512\dfrac{2}{5} m wide. Find the perimeter of the field.

Answer

Given,

Length of the field = 161216\dfrac{1}{2} m

Breadth of the field = 122512\dfrac{2}{5} m

Length = 1612 m =33216\dfrac{1}{2} \text { m }= \dfrac{33}{2} m and breadth =1225 m =625= 12\dfrac{2}{5}\text { m }= \dfrac{62}{5} m

Perimeter = 2 x (length + breadth)

=2×(332+625)=2×(33×52×5+62×25×2)=2×(16510+12410)=2×165+12410=2×28910=2895=5745 m= 2 \times \left(\dfrac{33}{2} + \dfrac{62}{5}\right) \\[1em] = 2 \times \left(\dfrac{33 \times 5}{2 \times 5} + \dfrac{62 \times 2}{5 \times 2}\right) \\[1em] = 2 \times \left(\dfrac{165}{10} + \dfrac{124}{10}\right) \\[1em] = 2 \times \dfrac{165 + 124}{10} \\[1em] = 2 \times \dfrac{289}{10} \\[1em] = \dfrac{289}{5} = 57\dfrac{4}{5} \text{ m}

Hence, the perimeter of the field is 5745 m .57\dfrac{4}{5} \text { m }.

Question 11

Sugar costs ₹ 371237\dfrac{1}{2} per kg. Find the cost of 8348\dfrac{3}{4} kg sugar.

Answer

Given,

Cost of sugar per kg = ₹ 371237\dfrac{1}{2}

Quantity of sugar = 8348\dfrac{3}{4} kg

Cost of 8348\dfrac{3}{4} kg sugar = Cost per kg × Quantity

=3712×834=752×354=75×352×4=26258=32818= 37\dfrac{1}{2} \times 8\dfrac{3}{4} \\[1em] = \dfrac{75}{2} \times \dfrac{35}{4} \\[1em] = \dfrac{75 \times 35}{2 \times 4} = \dfrac{2625}{8} \\[1em] = 328\dfrac{1}{8}

Hence, the cost of 8348\dfrac{3}{4} kg sugar is ₹ 32818328\dfrac{1}{8}.

Question 12

A motor cycle runs 311431\dfrac{1}{4} km consuming 1 litre of petrol. How much distance will it run consuming 1351\dfrac{3}{5} litre of petrol?

Answer

Given,

Distance run on 1 litre of petrol = 311431\dfrac{1}{4} km

Quantity of petrol = 1351\dfrac{3}{5} litres

Distance run on 1351\dfrac{3}{5} litres = Distance per litre × Quantity of petrol

=3114×135=1254×85=125×84×5=100020=50 km= 31\dfrac{1}{4} \times 1\dfrac{3}{5} \\[1em] = \dfrac{125}{4} \times \dfrac{8}{5} \\[1em] = \dfrac{125 \times 8}{4 \times 5} = \dfrac{1000}{20} \\[1em] = 50 \text{ km}

Hence, the motor cycle will run 50 km.

Question 13

A rectangular park has length = 232523\dfrac{2}{5} m and breadth = 162316\dfrac{2}{3} m. Find the area of the park.

Answer

Given,

Length of the park = 232523\dfrac{2}{5} m

Breadth of the park = 162316\dfrac{2}{3} m

Area = length × breadth

Area =2325×1623=1175×503=39×10=390 m2.\text{Area } = 23\dfrac{2}{5} \times 16\dfrac{2}{3} \\[1em] = \dfrac{117}{5} \times \dfrac{50}{3} \\[1em] = 39 \times 10 \\[1em] = 390 \text{ m}^2.

Hence, the area of the park is 390 m2.

Question 14

Each of 40 identical boxes weighs 4454\dfrac{4}{5} kg. Find the total weight of all the boxes.

Answer

Given,

Number of identical boxes = 40

Weight of each box = 4454\dfrac{4}{5} kg

Total weight = Number of boxes × Weight of each box

Total weight =40×445=40×245= 40 \times 4\dfrac{4}{5} = 40 \times \dfrac{24}{5}

= 40×245=9605=192 kg\dfrac{40 \times 24}{5} = \dfrac{960}{5} = 192 \text{ kg}

Hence, the total weight of all the boxes is 192 kg.

Question 15

Out of 24 kg of wheat, 56\dfrac{5}{6} th of wheat is consumed. Find how much wheat is still left?

Answer

Given,

Total quantity of wheat = 24 kg

Fraction of wheat consumed = 56\dfrac{5}{6}

Fraction of wheat left =156=656=16= 1 - \dfrac{5}{6} = \dfrac{6 - 5}{6} = \dfrac{1}{6}

Wheat left = Fraction left × Total quantity

Wheat left =16×24=4= \dfrac{1}{6} \times 24 = 4 kg

Hence, 4 kg of wheat is still left.

Question 16

A rod of length 2252\dfrac{2}{5} metre is divided into five equal parts. Find the length of each part so obtained.

Answer

Given,

Total length of the rod = 2252\dfrac{2}{5} metre

Number of equal parts = 5

Length of each part = Total length ÷ Number of parts

Length of each part =225÷5=125÷5= 2\dfrac{2}{5} \div 5 = \dfrac{12}{5} \div 5

= 125×15=1225 m\dfrac{12}{5} \times \dfrac{1}{5} = \dfrac{12}{25} \text{ m}

Hence, the length of each part is 1225\dfrac{12}{25} m.

Question 17

If A = 3383\dfrac{3}{8} and B = 6586\dfrac{5}{8}, find:

(i) A ÷ B

(ii) B ÷ A.

Answer

A =338=278= 3\dfrac{3}{8} = \dfrac{27}{8} and B =658=538= 6\dfrac{5}{8} = \dfrac{53}{8}

(i) A ÷ B =278÷538=278×853=2753= \dfrac{27}{8} \div \dfrac{53}{8} = \dfrac{27}{8} \times \dfrac{8}{53} = \dfrac{27}{53}

Hence, A ÷ B = 2753\dfrac{27}{53}.

(ii) B ÷ A

=538÷278=538×827=5327=12627= \dfrac{53}{8} \div \dfrac{27}{8} \\[1em] = \dfrac{53}{8} \times \dfrac{8}{27}\\[1em] = \dfrac{53}{27} = 1\dfrac{26}{27}

Hence, B ÷ A = 126271\dfrac{26}{27}.

Question 18

Cost of 3573\dfrac{5}{7} litres of oil is ₹ 831283\dfrac{1}{2}. Find the cost of one litre oil.

Answer

Given,

Quantity of oil = 3573\dfrac{5}{7} litres

Cost of 3573\dfrac{5}{7} litres of oil = ₹ 831283\dfrac{1}{2}

Cost of one litre = Total cost ÷ Quantity of oil

Cost of one litre =8312÷357= 83\dfrac{1}{2} \div 3\dfrac{5}{7}

=1672÷267=1672×726=167×72×26=116952=222552= \dfrac{167}{2} \div \dfrac{26}{7} \\[1em] = \dfrac{167}{2} \times \dfrac{7}{26} \\[1em] = \dfrac{167 \times 7}{2 \times 26} = \dfrac{1169}{52} \\[1em] = 22\dfrac{25}{52}

Hence, the cost of one litre of oil is ₹ 22255222\dfrac{25}{52}.

Question 19

The product of two numbers is 205720\dfrac{5}{7}. If one of these numbers is 6236\dfrac{2}{3}, find the other.

Answer

Let the other number be x.

Then, 623×x=20576\dfrac{2}{3} \times x = 20\dfrac{5}{7}

x=2057÷623=1457÷203=1457×320=145×37×20=435140=8728=3328\Rightarrow x = 20\dfrac{5}{7} \div 6\dfrac{2}{3} \\[1em] = \dfrac{145}{7} \div \dfrac{20}{3} \\[1em] = \dfrac{145}{7} \times \dfrac{3}{20} \\[1em] = \dfrac{145 \times 3}{7 \times 20} = \dfrac{435}{140} \\[1em] = \dfrac{87}{28} = 3\dfrac{3}{28}

Hence, the other number is 33283\dfrac{3}{28}.

Question 20

By what number should 5565\dfrac{5}{6} be multiplied to get 3133\dfrac{1}{3}?

Answer

Let the required number be x.

Then, 556×x=3135\dfrac{5}{6} \times x = 3\dfrac{1}{3}

x=313÷556=103÷356=103×635=10×63×35=60105=47\Rightarrow x = 3\dfrac{1}{3} \div 5\dfrac{5}{6} \\[1em] = \dfrac{10}{3} \div \dfrac{35}{6} \\[1em] = \dfrac{10}{3} \times \dfrac{6}{35} \\[1em] = \dfrac{10 \times 6}{3 \times 35} = \dfrac{60}{105} \\[1em] = \dfrac{4}{7}

Hence, the required number is 47\dfrac{4}{7}.

PrevNext