Roshan alone can build a fence in 20 days He starts the work and leaves it after 5 days - Maths - Direct and Inverse Proportions

Question

Roshan alone can build a fence in 20 days He starts the work and
leaves it after 5 days Ramesh does the remaining work in 12 days
How long will it take if Ramesh did the whole work alone? How long
will it take if Roshan and Ramesh work together from the
beginning?

Duke Biswass · Accepted Answer

work done by Roshan in 1 day = 1/20
work done by Roshan in 5 days = 5/20 = 1/4
work left to be done = 1 - 1/4 = 3/4
Time taken by Ramesh to do 3/4 of the work = 12 days
Hence time taken by Ramesh to do the whole work alone =
12Ã—4/3 = 16 days
Work done in 1 day if both Roshan and Ramesh work together =
1/20 + 1/16 = 9/80
Hence time taken by both to finish the work together = 80/9 = 8
88 days

Roshan alone can build a fence in 20 days. He starts the work and leaves it after 5 days.Ramesh does the remaining work in 12 days. How long will it take if Ramesh did the whole work alone? How long will it take if Roshan and Ramesh work together from the beginning?