Zen can finish a work in 20 days. He start doing the work and after 6 days John joined him. If both of them together completed the remaining work in 7 days, then in how many days can John alone finish 80% of the same work?
Answer & explanation
Correct answer: option 2
Let total work = 20
Zen can do it in 20 days, therefore,
Efficiency of Zen = 1 w/d
Work done by Zen in 6 days = 6
Remaining work = 20 - 6 = 14
Remaining work done by Zen + John in 7 days
Efficiency of Zen + John = \(\frac{14}{7}\) = 2 w/d
Efficiency of John = 2 - 1 = 1
John will do 80% work in = \(\frac{20\;×\;4}{5\;×\;1}\) = 16 days