A can do a piece of work n 7 days of 9 hours each and B alone 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?
2days
3days
4days
None of these
Explanation:
A can complete the work in (7*9) = 63 days
B can complete the work in (6*7) = 42 days
= > As one hours work = 1/63 and
Bs one hour work = 1/42
(A+B)s one hour work = 1/63+1/42 = 5/126
Therefore, Both can finish the work in 126/5 hours.
Number of days of 8 2/5 hours each = (126*5/(5*42)) = 3 days
A can complete the work in (7*9) = 63 days
B can complete the work in (6*7) = 42 days
= > As one hours work = 1/63 and
Bs one hour work = 1/42
(A+B)s one hour work = 1/63+1/42 = 5/126
Therefore, Both can finish the work in 126/5 hours.
Number of days of 8 2/5 hours each = (126*5/(5*42)) = 3 days