72 Men Do Piece Of Work In 25 Days

72 men do a piece of work in 25 days. In how many days will 30 men do the same work?

Answers:

Men : Days :: men : Days

72     :  25    ::  30   :    x

∴ By inverse proportion

72 × 25 = 30  × x

⇒ x = (25 × 72)/30

= 60 days