Question:A can do a piece of work in 7 days of 9 hours each and B can do it in 6 days of 7 hours each. How long will they take to do it, working together 8 2/5 hours a day ?
A 3 days
B 4 days
C 4 1/2 days
D None of these
+ Explanationsolution:
A can complete the work in `(7 xx 9)` hrs = 63 hrs.
B can complete the work in `(6 xx 7)` hrs = 42 hrs.
`:.` A's 1 hour's work = `1/63`
& B's 1 hour's work = `1/42`.
`(A + B)`'s 1 hour's work = `(1/63 + 1/42)`
= `5/126`.
`:.` Both will finish the work in `(126/5)` hrs.
Number of days of `8 2/5` hrs each = `(126/5 xx 5/42)`
= 3 days.
