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
The correct answer is Option (2) → 0.179
Take one complete work as 1 unit. A person who finishes it in \(n\) minutes does \(\frac{1}{n}\) unit per minute, and the average is the total of the four rates divided by 4.
Rates: \(\displaystyle \frac{1}{4},\ \frac{1}{5},\ \frac{1}{6},\ \frac{1}{10}\) unit per minute
Total \(\displaystyle =\frac{15+12+10+6}{60}=\frac{43}{60}\)
Average \(\displaystyle =\frac{43}{60}\div4=\frac{43}{240}\approx0.179\)