CDS 2018 PYQ with Answer — If A:B = 1:2, B:C = 3:4, C:D = 2:3 and D:E = 3:4, then what is B:E eq…

2018 · Q24

If A:B = 1:2, B:C = 3:4, C:D = 2:3 and D:E = 3:4, then what is B:E equal to?

Elementary MathematicsRatio and Proportion

A3:2
B1:8
C3:8
D4:1

Explanation

Write B:E as a telescoping product of the linked ratios: B/E = (B/C) × (C/D) × (D/E). The given links are B:C = 3:4, C:D = 2:3 and D:E = 3:4, so B/E = (3/4) × (2/3) × (3/4). The numerator is 3 × 2 × 3 = 18 and the denominator is 4 × 3 × 4 = 48, giving 18/48 = 3/8. The first ratio A:B is not needed for B:E — a common red herring. Hence option (C) 3:8.