If 20 men can build a water fountain 56 metres long in 6 days, what length of a similar water fountain can be built by 35 men in 3 days?	Options
A) 40 m	B) 44 m	C) 47 m	D) 49 m	E) 50 m

Rationale: explanation : let the required length be x metres more men , more length built ( direct proportion ) less days , less length built ( direct proportion ) men 20 : 35 days 6 : 3 : : 56 : x therefore ( 20 x 6 x x ) = ( 35 x 3 x 56 ) x = ( 35 x 3 x 56 ) / 120 = 49 hence , the required length is 49 m . answer : d
Answer: D