When x is added to each of 10, 23, 15 and 33, the sums obtained in this order are in proportion. The value of (x + 5) is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 8.
(10 + x) : (23 + x) :: (15 + x) : (33 + x)
⇒ (10 + x)/(23 + x) = (15 + x)/(33 + x)
Cross-multiply:
(10 + x)(33 + x) = (23 + x)(15 + x)
Solve:
330 + 10x + 33x + x² = 345 + 23x + 15x + x²
⇒ 330 + 43x = 345 + 38x
⇒ 43x − 38x = 345 − 330
⇒ 5x = 15 ⇒ x = 3
So, x + 5 = 8