Multiple choice

Out of three numbers, the ratio of the first and the second numbers is 3 : 4 and the ratio of the second and the third numbers is 5 : 6. If the difference between the first and the third numbers is 1125, find the average of the second and third numbers.

  1. 2750

  2. 2507

  3. 2075

  4. 2570

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

Let the three numbers be a, b, c in the ratios 3:4 and 5:6. To combine: a:b = 15:20 and b:c = 20:24, giving a:b:c = 15:20:24. Let k be the common multiplier. Then a=15k, b=20k, c=24k. Difference c-a = 9k = 1125, so k = 125. Average of b and c = (20k+24k)/2 = 22k = 22×125 = 2750. Option A is correct.