If 50 boys can finish a work in 30 days by working 6 hours per day, then how many hours per day should 25 days work to finish that work within 24 days?

15 hours

Formula to be used here,

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

where, M = No. of men, D = No. of days, H = No. of hours,

Putting in the values,

⇒ 50 x 30 x 6 = 25 x 24 x \( { H}_{2 } \)

⇒ \( { H}_{2 } \) = 15 hours.