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Mathematics

Three years hence, the ages of Radha and Meena will be in the ratio 5 : 2. If the sum of their present ages is 62 years, their ages, 2 years ago, were:

  1. 43 years and 19 years

  2. 41 years and 17 years

  3. 40 years and 16 years

  4. none of these

Quadratic Equations

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Answer

none of these

Reason

Let the present ages of Radha and Meena be a and b.

It is given, three years hence, the ages of Radha and Meena will be in the ratio 5:2.

a+3b+3=522(a+3)=5(b+3)2a+6=5b+152a=5b+1562a=5b+9a=5b+92 .......... (1)\Rightarrow \dfrac{a + 3}{b + 3} = \dfrac{5}{2}\\[1em] \Rightarrow 2(a + 3) = 5(b + 3)\\[1em] \Rightarrow 2a + 6 = 5b + 15\\[1em] \Rightarrow 2a = 5b + 15 - 6\\[1em] \Rightarrow 2a = 5b + 9\\[1em] \Rightarrow a = \dfrac{5b + 9}{2} \space ………. \space (1)

The sum of their present ages = 62 years.

⇒ a + b = 62

Substituting the value of a from equation (1), we get

5b+92\dfrac{5b + 9}{2} + b = 62

⇒ 5b + 9 + 2b = 124

⇒ 7b + 9 = 124

⇒ 7b = 124 - 9

⇒ 7b = 115

⇒ b = 1157\dfrac{115}{7}

Substituting the value of b in equation (1),

a=5×1157+92a=575+6314a=63814a=3197\Rightarrow a = \dfrac{5 \times \dfrac{115}{7} + 9}{2}\\[1em] \Rightarrow a = \dfrac{575 + 63}{14}\\[1em] \Rightarrow a = \dfrac{638}{14}\\[1em] \Rightarrow a = \dfrac{319}{7}\\[1em]

Radha's age 2 years ago = a - 2 = 31972=319147=3057=43.57\dfrac{319}{7} - 2 = \dfrac{319 - 14}{7} = \dfrac{305}{7} = 43.57

Meena's age 2 years ago = b - 2 = 11572=115147=1017=14.42\dfrac{115}{7} - 2 = \dfrac{115 - 14}{7} = \dfrac{101}{7} = 14.42

Hence, option 4 is the correct option.

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