A can complete a work in 4 minutes. B in 5 minutes, C in 6 minutes and D in 10 minutes respectively. The average number of units of work completed by them per minute will be
Answer & explanation
Correct answer: option 2
Let total work = 1 unit
Here, \(\frac{Work}{Time}\) = Efficiency
Efficiency of A = \(\frac{1}{4}\) unit/min
Efficiency of B = \(\frac{1}{5}\) unit/min
Efficiency of C = \(\frac{1}{6}\) unit/min
Efficiency of D = \(\frac{1}{10}\) unit/min
Efficiency of A, B, C & D together = $\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+\frac{1}{10}=\frac{43}{60}$ unit/min
Average number of units of work completed by them per minute = \(\frac{Efficiency\;of\;All\;together}{Number\;of\;person}\) = $\frac{43}{60×4}=0.179$