$20$ men can complete a piece of work in $30$ days, working $9$ hours daily. How many men are required to…
$20$ men can complete a piece of work in $30$ days, working $9$ hours daily. How many men are required to finish a job that is $\dfrac{2}{3}$ as large in $20$ days, working $6$ hours daily?
$24$
$28$
$30$
$36$
Solution
Original work units $= 20 \times 30 \times 9 = 5400$ man-hours. New job size $= \dfrac{2}{3} \times 5400 = 3600$ man-hours. So $m \times 20 \times 6 = 3600 \Rightarrow m = \dfrac{3600}{120} = 30$ men.