If 20 men can build a wall 112 metres long in 6 days, what length of a similar wall can be built by 30 men in 3 days? Choose the correct choice from the following options:
A) 65 mtr . B) 84 mtr C) 70 mtr . D) 78 mtr . E) 17 mtr .

Rationale: 20 men is 6 days can build 112 metres 30 men in 3 days can build = 112 * ( 30 / 20 ) x ( 3 / 6 ) = 84 meters answer : b .
Answer: B