Multiple choice

Present ages of father and son are in the ratio 5 : 1, respectively. Seven years later, this ratio will become 3 : 1. What is the son's present age (in years)?

  1. 8

  2. 7

  3. 6

  4. 5

  5. None of these

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let ages be 5x and x. After 7 years, (5x+7)/(x+7) = 3/1. 5x+7 = 3x+21, so 2x = 14, x = 7. The son's age is 7.

AI explanation

Let the present ages of the father and son be 5x and 1x respectively. Seven years later, their ages will be 5x plus 7 and x plus 7, so we set up the proportion (5x plus 7) divided by (x plus 7) equals 3 divided by 1. Cross-multiplying yields 5x plus 7 equals 3x plus 21, and simplifying this gives 2x equals 14, meaning x is 7. Therefore, the son's present age is x, which is 7 years.