What number should be subtracted from each of the numbers 23, 30, 57 and 78 so that the resultant numbers are in proportion ?
A4
B3
C6
D7
Answer:
C. 6
Read Explanation:
Consider x to be the number to be subtracted from each term
So,
23–x, 30–x, 57–x and 78–x are proportional
(23–x) : (30–x) :: (57–x) : (78–x)
(23–x)(78–x) = (30–x)(57–x)
1794 - 23x - 78x + x² = 1710 - 30x - 57x + x²
1794 - 101x + x² = 1710 - 87x + x²
14x = 84
x = 6
