Multiple choice

Ratio of the ages of A and B 3 years ago was 3 : 7 and ratio of the present ages of A and B is 2 : 4. What will be the age of B after 5 years?

  1. 24

  2. 29

  3. 25

  4. 27

  5. 23
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let present ages be A and B. 3 years ago: (A-3)/(B-3) = 3/7. Present: A/B = 2/4 = 1/2, so B = 2A. Substitute: (A-3)/(2A-3) = 3/7. 7A - 21 = 6A - 9. A = 12. B = 24. Age of B after 5 years = 24 + 5 = 29.

AI explanation

Let the present ages of A and B be 2x and 4x years, which means their ages 3 years ago were 2x minus 3 and 4x minus 3. Using the ratio from 3 years ago, we set up the equation 2x minus 3 divided by 4x minus 3 equals 3 divided by 7, leading to 14x minus 21 equals 12x minus 9. Solving this gives 2x equals 12, so x equals 6, making the present age of B 4 times 6 which is 24 years. Adding 5 years to her present age gives B's future age as 29 years.

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