Multiple choice

The ratio of the age of Rock to that of Pock is known to be 6 : 5. Which of the following can be the possible ratio of the age of Rock to that of Pock 10 years from now?

  1. 9 : 7

  2. 17 : 11

  3. 19 : 14

  4. 23 : 21

  5. 37 : 27

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

Let ages be 6k and 5k. After 10 years, the ratio is (6k+10)/(5k+10). Testing options: for 23:21, (6k+10)/(5k+10) = 23/21 leads to 126k + 210 = 115k + 230, so 11k = 20, k = 20/11. Since k must be a positive number, this is a possible ratio.