When the same number is subtracted from 6, 8, 12, and 20, the resulting numbers are in proportion. Find the number subtracted.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 4.
Concept used:
If a, b, c, and d are in proportion then
a : b :: c : d
a/b = c/d
Calculations:
Let the number subtracted be x.
So,
⇒ (6 - x)/(8 - x) = (12 - x)/(20 - x)
⇒ 120 - 20x - 6x + x2 = 96 - 12x - 8x + x2
⇒ 120 - 96 = 26x - 20x
⇒ 24 = 6x
⇒ x = 4