KnowledgeBoat Logo
|
OPEN IN APP

Chapter 2

Fractions - Exercise 2(B)

Class - 7 RS Aggarwal Mathematics Solutions



Exercise 2(B)

Question 1(i)

Find the reciprocal of :

1317\dfrac{13}{17}

Answer

We have:

1317\dfrac{13}{17}

To find the reciprocal of a number, we interchange its numerator and denominator.

1317\dfrac{13}{17} = 1713\dfrac{17}{13}

= 1413[Converting improper to mixed fraction]1\dfrac{4}{13} \hspace{2cm}\text{[Converting improper to mixed fraction]}

∴ The reciprocal of 1317\dfrac{13}{17} is 14131\dfrac{4}{13}

Question 1(ii)

Find the reciprocal of :

3313\dfrac{3}{313}

Answer

We have:

3313\dfrac{3}{313}

Interchanging its numerator and denominator we get,

3313\dfrac{3}{313} = 3133\dfrac{313}{3}

= 10413[Converting improper to mixed fraction]104\dfrac{1}{3} \hspace{2cm}\text{[Converting improper to mixed fraction]}

∴ The reciprocal of 3313\dfrac{3}{313} is 10413104\dfrac{1}{3}

Question 1(iii)

Find the reciprocal of :

217

Answer

We have:

217

This can be written as 2171\dfrac{217}{1}

Interchanging its numerator and denominator we get,

2171\dfrac{217}{1} = 1217\dfrac{1}{217}

∴ The reciprocal of 2171\dfrac{217}{1} is 1217\dfrac{1}{217}

Question 1(iv)

Find the reciprocal of :

11024\dfrac{1}{1024}

Answer

We have:

11024\dfrac{1}{1024}

Interchanging its numerator and denominator we get,

11024\dfrac{1}{1024} = 10241\dfrac{1024}{1} = 1024

∴ The reciprocal of 11024\dfrac{1}{1024} is 1024

Question 1(v)

Find the reciprocal of :

3133\dfrac{1}{3}

Answer

We have:

313=103[Converting mixed to improper fraction]3\dfrac{1}{3} = \dfrac{10}{3} \hspace{1.5cm}\text{[Converting mixed to improper fraction]}

Interchanging its numerator and denominator we get,

103\dfrac{10}{3} = 310\dfrac{3}{10}

∴ The reciprocal of 103\dfrac{10}{3} is 310\dfrac{3}{10}

Question 1(vi)

Find the reciprocal of :

1111111\dfrac{1}{11}

Answer

We have:

1111111\dfrac{1}{11} = 12211[Converting mixed to improper fraction]\dfrac{122}{11} \hspace{1.5cm}\text{[Converting mixed to improper fraction]}

Interchanging its numerator and denominator we get,

12211=11122\dfrac{122}{11} = \dfrac{11}{122}

∴ The reciprocal of 12211\dfrac{122}{11} is 11122\dfrac{11}{122}

Question 1(vii)

Find the reciprocal of :

1121\dfrac{1}{2}

Answer

We have:

112=32[Converting mixed to improper fraction]1\dfrac{1}{2} = \dfrac{3}{2} \hspace{1.5cm}\text{[Converting mixed to improper fraction]}

Interchanging its numerator and denominator we get,

32\dfrac{3}{2} = 23\dfrac{2}{3}

∴ The reciprocal of 32\dfrac{3}{2} is 23\dfrac{2}{3}

Question 1(viii)

Find the reciprocal of :

12518125\dfrac{1}{8}

Answer

We have:

12518=10018[Converting mixed to improper fraction]125\dfrac{1}{8} = \dfrac{1001}{8} \hspace{1.5cm}\text{[Converting mixed to improper fraction]}

Interchanging its numerator and denominator we get,

10018\dfrac{1001}{8} = 81001\dfrac{8}{1001}

∴ The reciprocal of 10018\dfrac{1001}{8} is 81001\dfrac{8}{1001}

Question 2(i)

Divide :

12\dfrac{1}{2} ÷ 13\dfrac{1}{3}

Answer

We have:

=12÷13=12×31[Reciprocal of 13 is 31]=1×32×1=32=112\begin{array}{ll} \phantom{=} \dfrac{1}{2} ÷ \dfrac{1}{3} \\\\ = \dfrac{1}{2} \times \dfrac{3}{1} & [\text{Reciprocal of } \dfrac{1}{3} \text{ is } \dfrac{3}{1}] \\\\ = \dfrac{1 \times 3}{2 \times 1} \\\\ = \dfrac{3}{2} \\\\ = 1\dfrac{1}{2} \end{array}

∴ The answer is 1121\dfrac{1}{2}

Question 2(ii)

Divide :

314\dfrac{3}{14} ÷ 1142\dfrac{11}{42}

Answer

We have:

=314÷1142=314×4211[Reciprocal of 1142 is 4211]=3×4214×11=3×31×11[Simplifying 42 and 14 ⇒ Divide by 14]=911\begin{array}{ll} \phantom{=} \dfrac{3}{14} ÷ \dfrac{11}{42} \\\\ = \dfrac{3}{14} \times \dfrac{42}{11} & [\text{Reciprocal of } \dfrac{11}{42} \text{ is } \dfrac{42}{11}] \\\\ = \dfrac{3 \times 42}{14 \times 11} \\\\ = \dfrac{3 \times 3}{1 \times 11} & \text{[Simplifying 42 and 14 ⇒ Divide by 14]} \\\\ = \dfrac{9}{11} \\\\ \end{array}

∴ The answer is 911\dfrac{9}{11}

Question 2(iii)

Divide :

1 ÷ 6236\dfrac{2}{3}

Answer

We have:

=1÷623=1÷203[Converting mixed to improper fraction]=1×320[Reciprocal of 203 is 320]=11×320=1×31×20=320\begin{array}{ll} \phantom{=} 1 ÷ 6\dfrac{2}{3} \\\\ = 1 ÷ \dfrac{20}{3} & \text{[Converting mixed to improper fraction]} \\\\ = 1 \times \dfrac{3}{20} & [\text{Reciprocal of } \dfrac{20}{3} \text{ is } \dfrac{3}{20}] \\\\ = \dfrac{1}{1} \times \dfrac{3}{20} \\\\ = \dfrac{1 \times 3}{1 \times 20} \\\\ = \dfrac{3}{20} \\\\ \end{array}

∴ The answer is 320\dfrac{3}{20}

Question 2(iv)

Divide :

131313\dfrac{1}{3} ÷ 10

Answer

We have:

=1313÷10=403÷10[Converting mixed to improper fraction]=403×110[Reciprocal of 10 is 110]=43×11[Simplifying 40 and 10 ⇒ Divide by 10]=4×13×1=43=113\begin{array}{ll} \phantom{=} 13\dfrac{1}{3} ÷ 10 \\\\ = \dfrac{40}{3} ÷ 10 & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{40}{3} \times \dfrac{1}{10} & [\text{Reciprocal of } 10 \text{ is } \dfrac{1}{10}] \\\\ = \dfrac{4}{3} \times \dfrac{1}{1} & \text{[Simplifying 40 and 10 ⇒ Divide by 10]} \\\\ = \dfrac{4 \times 1}{3 \times 1} \\\\ = \dfrac{4}{3} \\\\ = 1\dfrac{1}{3} \end{array}

∴ The answer is 1131\dfrac{1}{3}

Question 2(v)

Divide :

1211212\dfrac{1}{12} ÷ 536\dfrac{5}{36}

Answer

We have:

=12112÷536=14512÷536[Converting mixed to improper fraction]=14512×365[Reciprocal of 536 is 365]=2912×361[Simplifying 145 and 5 ⇒ Divide by 5]=291×31[Simplifying 36 and 12 ⇒ Divide by 12]=29×31×1=871=87\begin{array}{ll} \phantom{=} 12\dfrac{1}{12} ÷ \dfrac{5}{36} \\\\ = \dfrac{145}{12} ÷ \dfrac{5}{36} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{145}{12} \times \dfrac{36}{5} & [\text{Reciprocal of } \dfrac{5}{36} \text{ is } \dfrac{36}{5}] \\\\ = \dfrac{29}{12} \times \dfrac{36}{1} & \text{[Simplifying 145 and 5 ⇒ Divide by 5]} \\\\ = \dfrac{29}{1} \times \dfrac{3}{1} & \text{[Simplifying 36 and 12 ⇒ Divide by 12]} \\\\ = \dfrac{29 \times 3}{1 \times 1} \\\\ = \dfrac{87}{1} \\\\ = 87 \end{array}

∴ The answer is 87

Question 2(vi)

Divide :

1346\dfrac{13}{46} ÷ 21112\dfrac{1}{11}

Answer

We have:

=1346÷2111=1346÷2311[Converting mixed to improper fraction]=1346×1123[Reciprocal of 2311 is 1123]=13×1146×23=1431058\begin{array}{ll} \phantom{=} \dfrac{13}{46} ÷ 2\dfrac{1}{11} \\\\ = \dfrac{13}{46} ÷ \dfrac{23}{11} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{13}{46} \times \dfrac{11}{23} & [\text{Reciprocal of } \dfrac{23}{11} \text{ is } \dfrac{11}{23}] \\\\ = \dfrac{13 \times 11}{46 \times 23} \\\\ = \dfrac{143}{1058} \end{array}

∴ The answer is 1431058\dfrac{143}{1058}

Question 2(vii)

Divide :

2031\dfrac{20}{31} ÷ 54

Answer

We have:

=2031÷54=2031×154[Reciprocal of 54 is 154]=1031×127[Simplifying 20 and 54 ⇒ Divide by 2]=10×131×27=10837\begin{array}{ll} \phantom{=} \dfrac{20}{31} ÷ 54 \\\\ = \dfrac{20}{31} \times \dfrac{1}{54} & [\text{Reciprocal of } 54 \text{ is } \dfrac{1}{54}] \\\\ = \dfrac{10}{31} \times \dfrac{1}{27} & \text{[Simplifying 20 and 54 ⇒ Divide by 2]} \\\\ = \dfrac{10 \times 1}{31 \times 27} \\\\ = \dfrac{10}{837} \end{array}

∴ The answer is 10837\dfrac{10}{837}

Question 2(viii)

Divide :

9459\dfrac{4}{5} ÷ 323253\dfrac{23}{25}

Answer

We have:

=945÷32325=495÷9825[Converting mixed to improper fraction]=495×2598[Reciprocal of 9825 is 2598]=15×252[Simplifying 49 and 98 ⇒ Divide by 49]=11×52[Simplifying 25 and 5 ⇒ Divide by 5]=1×51×2=52=212\begin{array}{ll} \phantom{=} 9\dfrac{4}{5} ÷ 3\dfrac{23}{25} \\\\ = \dfrac{49}{5} ÷ \dfrac{98}{25} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{49}{5} \times \dfrac{25}{98} & [\text{Reciprocal of } \dfrac{98}{25} \text{ is } \dfrac{25}{98}] \\\\ = \dfrac{1}{5} \times \dfrac{25}{2} & \text{[Simplifying 49 and 98 ⇒ Divide by 49]} \\\\ = \dfrac{1}{1} \times \dfrac{5}{2} & \text{[Simplifying 25 and 5 ⇒ Divide by 5]} \\\\ = \dfrac{1 \times 5}{1 \times 2} \\\\ = \dfrac{5}{2} \\\\ = 2\dfrac{1}{2} \end{array}

∴ The answer is 2122\dfrac{1}{2}

Question 2(ix)

Divide :

321232\dfrac{1}{2} ÷ 8348\dfrac{3}{4}

Answer

We have:

=3212÷834=652÷354[Converting mixed to improper fraction]=652×435[Reciprocal of 354 is 435]=132×47[Simplifying 65 and 35 ⇒ Divide by 5]=131×27[Simplifying 4 and 2 ⇒ Divide by 2]=13×21×7=267=357\begin{array}{ll} \phantom{=} 32\dfrac{1}{2} ÷ 8\dfrac{3}{4} \\\\ = \dfrac{65}{2} ÷ \dfrac{35}{4} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{65}{2} \times \dfrac{4}{35} & [\text{Reciprocal of } \dfrac{35}{4} \text{ is } \dfrac{4}{35}] \\\\ = \dfrac{13}{2} \times \dfrac{4}{7} & \text{[Simplifying 65 and 35 ⇒ Divide by 5]} \\\\ =\dfrac{13}{1} \times \dfrac{2}{7} & \text{[Simplifying 4 and 2 ⇒ Divide by 2]} \\\\ = \dfrac{13 \times 2}{1 \times 7} \\\\ = \dfrac{26}{7} \\\\ = 3\dfrac{5}{7} \end{array}

∴ The answer is 3573\dfrac{5}{7}

Question 2(x)

Divide :

81218\dfrac{1}{21} ÷ 1671\dfrac{6}{7}

Answer

We have:

=8121÷167=16921÷137[Converting mixed to improper fraction]=16921×713[Reciprocal of 137 is713]=1321×71[Simplifying 169 and 13 ⇒ Divide by 13]=133×11[Simplifying 7 and 21 ⇒ Divide by 7]=13×13×1=133=413\begin{array}{ll} \phantom{=} 8\dfrac{1}{21} ÷ 1\dfrac{6}{7} \\\\ = \dfrac{169}{21} ÷ \dfrac{13}{7} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{169}{21} \times \dfrac{7}{13} & [\text{Reciprocal of } \dfrac{13}{7} \text{ is} \dfrac{7}{13}] \\\\ = \dfrac{13}{21} \times \dfrac{7}{1} & \text{[Simplifying 169 and 13 ⇒ Divide by 13]} \\\\ = \dfrac{13}{3} \times \dfrac{1}{1} & \text{[Simplifying 7 and 21 ⇒ Divide by 7]} \\\\ = \dfrac{13 \times 1}{3 \times 1} \\\\ = \dfrac{13}{3} \\\\ = 4\dfrac{1}{3} \end{array}

∴ The answer is 4134\dfrac{1}{3}

Question 2(xi)

Divide :

63166\dfrac{3}{16} ÷ 3173\dfrac{1}{7}

Answer

We have:

=6316÷317=9916÷227[Converting mixed to improper fraction]=9916×722[Reciprocal of 227 is 722]=916×72[Simplifying 99 and 22 ⇒ Divide by 11]=9×716×2=6332=13132\begin{array}{ll} \phantom{=} 6\dfrac{3}{16} ÷ 3\dfrac{1}{7} \\\\ = \dfrac{99}{16} ÷ \dfrac{22}{7} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{99}{16} \times \dfrac{7}{22} & [\text{Reciprocal of } \dfrac{22}{7} \text{ is } \dfrac{7}{22}] \\\\ = \dfrac{9}{16} \times \dfrac{7}{2} & \text{[Simplifying 99 and 22 ⇒ Divide by 11]} \\\\ = \dfrac{9 \times 7}{16 \times 2} \\\\ = \dfrac{63}{32} \\\\ = 1\dfrac{31}{32} \end{array}

∴ The answer is 131321\dfrac{31}{32}

Question 2(xii)

Divide :

311153\dfrac{11}{15} ÷ 193519\dfrac{3}{5}

Answer

We have:

=31115÷1935=5615÷985[Converting mixed to improper fraction]=5615×598[Reciprocal of 985 is 598]=563×198[Simplifying 5 and 15 ⇒ Divide by 5]=43×17[Simplifying 56 and 98 ⇒ Divide by 14]=4×13×7=421\begin{array}{ll} \phantom{=} 3\dfrac{11}{15} ÷ 19\dfrac{3}{5} \\\\ = \dfrac{56}{15} ÷ \dfrac{98}{5} & \text{[Converting mixed to improper fraction]} \\\\ = \dfrac{56}{15} \times \dfrac{5}{98} & [\text{Reciprocal of } \dfrac{98}{5} \text{ is } \dfrac{5}{98}] \\\\ = \dfrac{56}{3} \times \dfrac{1}{98} & \text{[Simplifying 5 and 15 ⇒ Divide by 5]} \\\\ = \dfrac{4}{3} \times \dfrac{1}{7} & \text{[Simplifying 56 and 98 ⇒ Divide by 14]} \\\\ = \dfrac{4 \times 1}{3 \times 7} \\\\ = \dfrac{4}{21} \end{array}

∴ The answer is 421\dfrac{4}{21}

Question 3

By what fraction should 935\dfrac{9}{35} be multiplied to get 715\dfrac{7}{15} ?

Answer

Given:

The fraction by which 935\dfrac{9}{35} must be multiplied to get 715\dfrac{7}{15} = ?

Let the required fraction be x

Now we have,

935×x=715\dfrac{9}{35} \times x = \dfrac{7}{15}

x = 715÷935\dfrac{7}{15} ÷ \dfrac{9}{35}

=715×359[Reciprocal of 935 is 359]=73×79[Simplifying 35 and 15 ⇒ Divide by 5]=7×73×9=4927=12227\begin{array}{ll} = \dfrac{7}{15} \times \dfrac{35}{9} & [\text{Reciprocal of } \dfrac{9}{35} \text{ is } \dfrac{35}{9}] \\\\ = \dfrac{7}{3} \times \dfrac{7}{9} & \text{[Simplifying 35 and 15 ⇒ Divide by 5]} \\\\ = \dfrac{7 \times 7}{3 \times 9} \\\\ = \dfrac{49}{27} \\\\ = 1\dfrac{22}{27} \end{array}

∴ The answer is 122271\dfrac{22}{27}

Question 4

If the cost of 6146\dfrac{1}{4} m of cloth is ₹1421781421\dfrac{7}{8}, then find the cost of 1 metre of cloth.

Answer

Given:

Total cost = ₹142178=1137581421\dfrac{7}{8} = ₹\dfrac{11375}{8}

Total length = 614 m=254 m6\dfrac{1}{4}\text{ m} = \dfrac{25}{4}\text{ m}

Cost of 1 metre of cloth = ?

Cost of 1 metre of cloth = (Total cost) ÷ (Total length)

Substituting the values in above, we get:

Cost of 1 metre of cloth = ₹ 113758÷254\dfrac{11375}{8} ÷ \dfrac{25}{4} m

=(113758×425)[Reciprocal of 254 is 425]=(4558×41)[Simplifying 11375 and 25 ⇒ Divide by 25]=(4552×11)[Simplifying 4 and 8 ⇒ Divide by 4]=455×12×1=4552=22712\begin{array}{ll} = ₹\Big(\dfrac{11375}{8} \times \dfrac{4}{25}\Big) & [\text{Reciprocal of } \dfrac{25}{4} \text{ is } \dfrac{4}{25}] \\\\ = ₹\Big(\dfrac{455}{8} \times \dfrac{4}{1}\Big) & \text{[Simplifying 11375 and 25 ⇒ Divide by 25]} \\\\ = ₹\Big(\dfrac{455}{2} \times \dfrac{1}{1}\Big) & \text{[Simplifying 4 and 8 ⇒ Divide by 4]} \\\\ = ₹\dfrac{455 \times 1}{2 \times 1} \\\\ = ₹\dfrac{455}{2} \\\\ = ₹227\dfrac{1}{2} \end{array}

∴ The cost of 1 metre of cloth = ₹22712227\dfrac{1}{2}

Question 5

How many pieces of length 3573\dfrac{5}{7}m each can be cut from a wall paper 52 m long?

Answer

Given:

Piece length = 3573\dfrac{5}{7} m = 267\dfrac{26}{7} m [Converting mixed to improper fraction]\hspace{1.5cm}\text{[Converting mixed to improper fraction]}

Total length = 52 m

Number of pieces = ?

Number of pieces = (Total length) ÷ (Piece length)

Substituting the values in above, we get:

Number of pieces = 52 m ÷ 267\dfrac{26}{7} m

=(521×726)[Reciprocal of 267 is 726]=(21×71)[Simplifying 52 and 26 ⇒ Divide by 26]=(2×71×1)=141=14\begin{array}{ll} = \Big(\dfrac{52}{1} \times \dfrac{7}{26}\Big) & [\text{Reciprocal of } \dfrac{26}{7} \text{ is } \dfrac{7}{26}] \\\\ = \Big(\dfrac{2}{1} \times \dfrac{7}{1}\Big) & \text{[Simplifying 52 and 26 ⇒ Divide by 26]} \\\\ = \Big(\dfrac{2 \times 7}{1 \times 1}\Big) \\\\ = \dfrac{14}{1} \\\\ = 14 \end{array}

∴ Number of pieces = 14

Question 6

A log of wood 6276\dfrac{2}{7}m in length, was cut into 11 pieces. What is the length of each piece?

Answer

Given :

Total length of a log of wood = 6276\dfrac{2}{7} m = 447\dfrac{44}{7} m

Number of pieces = 11

Length of each piece = ?

Length of each piece = (Total length of a log of wood) ÷ (Number of pieces)

Substituting the values in above, we get:

Length of each piece = 447\dfrac{44}{7} m ÷ 11

=(447×111) m[Reciprocal of 11 is 111]=(47×11) m[Simplifying 44 and 11 ⇒ Divide by 11]=47 m\begin{array}{ll} = \Big(\dfrac{44}{7} \times \dfrac{1}{11}\Big)\text{ m} & [\text{Reciprocal of } 11 \text{ is } \dfrac{1}{11}] \\\\ = \Big(\dfrac{4}{7} \times \dfrac{1}{1}\Big)\text{ m} & \text{[Simplifying 44 and 11 ⇒ Divide by 11]} \\\\ = \dfrac{4}{7}\text{ m} \\\\ \end{array}

∴ The length of each piece = 47\dfrac{4}{7} m

Question 7

A car covers 64114641\dfrac{1}{4}km in 431843\dfrac{1}{8} litres of fuel. How much distance can this car cover in 1 litre of fuel ?

Answer

Given:

Total distance = 64114 km=25654641\dfrac{1}{4}\text{ km} = \dfrac{2565}{4} km

Total fuel = 4318 litres=3458 litres43\dfrac{1}{8}\text{ litres} = \dfrac{345}{8}\text{ litres}

Distance per litre = ?

Distance per litre = (Total distance) ÷ (Total fuel)

Substituting the values in above, we get:

Distance per litre = 25654 km÷3458 litres\dfrac{2565}{4}\text{ km} ÷ \dfrac{345}{8}\text{ litres}

=(25654×8345) km[Reciprocal of 3458 is 8345]=(25651×2345) km[Simplifying 8 and 4 ⇒ Divide by 4]=(1711×223) km[Simplifying 2565 and 345 ⇒ Divide by 15]=171×21×23 km=34223 km=142023 km\begin{array}{ll} = \Big(\dfrac{2565}{4} \times \dfrac{8}{345}\Big)\text{ km} & [\text{Reciprocal of } \dfrac{345}{8} \text{ is } \dfrac{8}{345}] \\\\ = \Big(\dfrac{2565}{1} \times \dfrac{2}{345}\Big)\text{ km} & \text{[Simplifying 8 and 4 ⇒ Divide by 4]} \\\\ = \Big(\dfrac{171}{1} \times \dfrac{2}{23}\Big)\text{ km} & \text{[Simplifying 2565 and 345 ⇒ Divide by 15]} \\\\ = \dfrac{171 \times 2}{1 \times 23} \text{ km} \\\\ = \dfrac{342}{23} \text{ km} \\\\ = 14\dfrac{20}{23} \text{ km} \end{array}

∴ The distance per litre of petrol = 14202314\dfrac{20}{23} km

Question 8

The area of a rectangular plot of land is 81745817\dfrac{4}{5}sq. m. If its breadth is 213421\dfrac{3}{4}m, find its length.

Answer

Given:

Area of rectangular plot of land = 81745 m2=40895 m2817\dfrac{4}{5}\text{ m}^2 = \dfrac{4089}{5}\text{ m}^2

Breadth = 2134 m=874 m21\dfrac{3}{4}\text{ m} = \dfrac{87}{4} \text{ m}

Length of rectangular plot of land = ?

Length of rectangular plot of land = (Area of rectangular plot of land) ÷ (Breadth)

Substituting the values in above, we get:

Length of rectangular plot of land = 40895 m2÷874 m\dfrac{4089}{5}\text{ m}^2 ÷ \dfrac{87}{4} \text{ m}

=(40895×487) m[Reciprocal of 874 is 487]=(475×41) m[Simplifying 2565 and 345 ⇒ Divide by 15]=47×45×1 m=1885 m=3735 m\begin{array}{ll} = \Big(\dfrac{4089}{5} \times \dfrac{4}{87}\Big)\text{ m} & [\text{Reciprocal of } \dfrac{87}{4} \text{ is } \dfrac{4}{87}] \\\\ = \Big(\dfrac{47}{5} \times \dfrac{4}{1}\Big)\text{ m} & \text{[Simplifying 2565 and 345 ⇒ Divide by 15]} \\\\ = \dfrac{47 \times 4}{5 \times 1} \text{ m} \\\\ = \dfrac{188}{5} \text{ m} \\\\ = 37\dfrac{3}{5}\text{ m} \end{array}

∴ The breadth of rectangular plot of land = 373537\dfrac{3}{5} m

Question 9

The area of a sheet of paper is 623710623\dfrac{7}{10} sq. cm. If its length is 2971029\dfrac{7}{10}cm, find its width.

Answer

Given:

Area of a sheet of paper = 623710 cm2=623710 cm2623\dfrac{7}{10}\text{ cm}^2 = \dfrac{6237}{10}\text{ cm}^2

Length = 29710 cm=29710 cm29\dfrac{7}{10}\text{ cm} = \dfrac{297}{10}\text{ cm}

Width = ?

The sheet of paper will be in rectangular shape,

∴ Area = Length x Width

Width = Area ÷ Length

Substituting the values in above, we get:

Width = 623710 cm2\dfrac{6237}{10}\text{ cm}^2 ÷ 29710 cm\dfrac{297}{10}\text{ cm}

=(623710×10297) cm[Reciprocal of 29710 is 10297]=(62371×1297) cm[Simplifying 10 and 10 ⇒ Divide by 1]=6237×11×297 cm=6237297 cm=21 cm\begin{array}{ll} = \Big(\dfrac{6237}{10} \times \dfrac{10}{297}\Big)\text{ cm} & [\text{Reciprocal of } \dfrac{297}{10} \text{ is } \dfrac{10}{297}] \\\\ = \Big(\dfrac{6237}{1} \times \dfrac{1}{297}\Big)\text{ cm} & \text{[Simplifying 10 and 10 ⇒ Divide by 1]} \\\\ = \dfrac{6237 \times 1}{1 \times 297} \text{ cm} \\\\ = \dfrac{6237}{297}\text{ cm} \\\\ = 21 \text{ cm} \end{array}

∴ The width of a sheet of paper = 21 cm

Question 10

A bundle of 500 sheets of paper has a net weight of 23102\dfrac{3}{10}kg. Find the weight of 1 sheet of paper.

Answer

Given:

Total weigth = 2310 kg=2310 kg2\dfrac{3}{10} \text{ kg} = \dfrac{23}{10} \text{ kg}

Number of sheets = 500

Weigth of 1 sheet of paper = (Total weigth) ÷ (Number of sheets)

Substituting the values in above, we get:

Weigth of 1 sheet of paper = 2310\dfrac{23}{10} kg ÷ 500

=(2310×1500) kg[Reciprocal of 500 is 1500]=23×110×500 kg=235000 kg\begin{array}{ll} = \Big(\dfrac{23}{10} \times \dfrac{1}{500}\Big)\text{ kg} & [\text{Reciprocal of } 500 \text{ is } \dfrac{1}{500}] \\\\ = \dfrac{23 \times 1}{10 \times 500} \text{ kg} \\\\ = \dfrac{23}{5000} \text{ kg} \end{array}

∴ The weigth of 1 sheet of paper = 235000\dfrac{23}{5000} kg

Question 11

A car travels 28312283\dfrac{1}{2} km in 4234\dfrac{2}{3} hours. How far does this car go in 1 hour, travelling at the same speed?

Answer

Given:

Total distance = 28312 km=5672 km283\dfrac{1}{2}\text{ km} = \dfrac{567}{2}\text{ km}

Total time = 423 hours=143 hours4\dfrac{2}{3}\text{ hours} = \dfrac{14}{3}\text{ hours}

Distance covered in 1 hour = ?

Distance covered in 1 hour = (Total distance) ÷ (Total time)

Substituting the values in above, we get:

Distance covered in 1 hour = 5672 km÷143 hours\dfrac{567}{2}\text{ km} ÷ \dfrac{14}{3}\text{ hours}

=(5672×314) km[Reciprocal of 143 is 314]=(812×32) km[Simplifying 567 and 14 ⇒ Divide by 7]=81×32×2 km=2434 km=6034 km\begin{array}{ll} = \Big(\dfrac{567}{2} \times \dfrac{3}{14}\Big) \text{ km} & [\text{Reciprocal of } \dfrac{14}{3} \text{ is } \dfrac{3}{14}] \\\\ = \Big(\dfrac{81}{2} \times \dfrac{3}{2}\Big) \text{ km} & \text{[Simplifying 567 and 14 ⇒ Divide by 7]} \\\\ = \dfrac{81 \times 3}{2 \times 2}\text{ km} \\\\ = \dfrac{243}{4}\text{ km} \\\\ = 60\dfrac{3}{4}\text{ km} \end{array}

∴ The distance covered in 1 hour = 603460\dfrac{3}{4} km

Question 12

The product of two fractions is 87258\dfrac{7}{25}. If one of them is 31153\dfrac{1}{15} find the other.

Answer

Given:

Let the two fractions be p and q.

p = 3115=46153\dfrac{1}{15} = \dfrac{46}{15}

Let the other fraction be q.

p x q = 8725=207258\dfrac{7}{25} = \dfrac{207}{25}

q = 20725\dfrac{207}{25} ÷ p [Solving for q]\hspace{2cm}\text{[Solving for q]}

Substituting the value of p, we get:

q = 20725÷4615\dfrac{207}{25} ÷ \dfrac{46}{15}

=20725×1546[Reciprocal of 4615 is 1546]=2075×346[Simplifying 15 and 25 ⇒ Divide by 5]=95×32[Simplifying 207 and 46 ⇒ Divide by 23]=9×35×2=2710=2710\begin{array}{ll} = \dfrac{207}{25} \times \dfrac{15}{46} & [\text{Reciprocal of } \dfrac{46}{15} \text{ is } \dfrac{15}{46}] \\\\ = \dfrac{207}{5} \times \dfrac{3}{46} & \text{[Simplifying 15 and 25 ⇒ Divide by 5]} \\\\ = \dfrac{9}{5} \times \dfrac{3}{2} & \text{[Simplifying 207 and 46 ⇒ Divide by 23]} \\\\ = \dfrac{9 \times 3}{5 \times 2} \\\\ = \dfrac{27}{10} \\\\ = 2\dfrac{7}{10} \end{array}

∴ The other fraction = 27102\dfrac{7}{10}

PrevNext