A and B can complete a certain work in 13 days and 26 days, respectively. They worked together for 4 days. C alone completed the remaining work in 7 days, A, B and C together can complete the same work in:
Answer & explanation
Correct answer: option 2
Efficiency of A + B = 2 + 1 = 3
Work done in 4 days = (efficiency of A + B) x No. of days
= 3 x 4 = 12
Remaining work = 26 - 12 = 14
This work is done by C alone in 7 days,
Then efficiency of C = \(\frac{work\; done}{no.\; of\; days}\)
= \(\frac{14}{7}\) = 2
Efficiency of A + B + C = 2 + 1 + 2 = 5
Time taken by A, B and C to complete the work = \(\frac{Total \; work}{efficiency}\)
= \(\frac{26}{5}\) = 5\(\frac{1}{5}\) days