40th B.P.S.C. (Pre) 1995

If a : b :: c : d then—

a(a + b) : b : (c + d)

b(a - b) : b :: (c - d):d✓ Correct

c(a + b + c) : d

d(a - c) : b :(d - a)

Explanation

If a : b :: c : d, then by the rule of componendo and dividendo- $$\frac{a-b}{b} = \frac{c-d}{d}$$ or (a – b) : b :: (c – d) : d Hence, option (b) is the correct answer. (461)

general-mental-ability