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Question

In a family, the sum of the ages of a father and son is 50 years. 10 years from now, the difference in their ages will be 20 years. Find the ratio of the son's age to the father's age.

The correct answer is
3:07

Father and Son Age Ratio Calculation

Problem Setup

Let the father's current age be $F$ and the son's current age be $S$.

We are given two conditions:

  • The sum of their current ages is 50 years: $F + S = 50$.
  • 10 years from now, the difference in their ages will be 20 years. In 10 years, their ages will be $F+10$ and $S+10$. The difference remains constant: $(F+10) - (S+10) = F - S$. Thus, $F - S = 20$.

Solving the Age Equations

We need to solve the system of linear equations:

  1. $F + S = 50$
  2. $F - S = 20$

Add equation (1) and equation (2):

$(F + S) + (F - S) = 50 + 20$

$2F = 70$

$F = \frac{70}{2} = 35$

Substitute the value of $F$ into equation (1):

$35 + S = 50$

$S = 50 - 35 = 15$

The father's current age is 35 years and the son's current age is 15 years.

Determining the Age Ratio

The question asks for the ratio of the son's age to the father's age.

Ratio $= S : F = 15 : 35$

Simplify the ratio by dividing both parts by their greatest common divisor, which is 5:

Ratio $= \frac{15 \div 5}{35 \div 5} = \frac{3}{7}$

The ratio is 3:7.

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Important Questions from Age

  1. The ages of two persons P and Q are in the ratio 5 : 7. Eight years ago, the ratio of P and Q was 7 : 13. The present ages of P and Q, respectively, are:

  2. One year ago, the ratio of the ages of A and B was 4 : 3. The ratio of their ages, after 7 years from now, will be 9 : 7. What is the present age (in years) of B?

  3. In 8 years, Subhash will be 3 times as old as he is now. After how many years will Subhash be 5 times as old as he is now?

  4. The average ages of parents and two children are 30 years and 8 years respectively. The average age of the family is

    A. 16 years

    B. 19 years

    C. 18 years

    D. 17 years

  5. A father is presently 3 times his daughter’s age. After 10 years he will be twice as old as her. Find the daughter’s present age.

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