If 25 persons can complete a work in 140 days, then how many persons will be required to complete the same work in 70 days?

50

Formula to be used:

⇒ \( { M}_{1 } \) x \( { D}_{1 } \) = \( { M}_{2 } \) x \( { D}_{2} \)

where, M = no. of men, D = No. of days.

Putting values in formula;

⇒ 25 x 140 = \( { M}_{2 } \) x 70

⇒ \( { M}_{2 } \) = 50 

Therefore, 50 men are required to complete the work in 70 days.