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?​

Answer 1

Answer:

For A

in 1 day, he can do 1/7 of work

in 9 hr, he can do 1/7 of work

in 1 hr, he can do 1/63 of work

in 8 2/5 hr, he can do (1/63)(42/5) = 0.1333 of work

For B

in 1 day, he can do 1/6 of work

in 7 hr, he can do 1/6 of work

in 1 hr, he can do 1/42 of work

in 8 2/5 hr, he can do (1/42)(42/5) = 0.2 of work.

when they work together

0.1333+0.2= 0.3333 of work in a day.

to complete the whole work,

i,e 0.3333(1/0.3333)

so in 1/0.3333 days whole work will complete

i,e in 3 days whole work will complete.

So, they will take 3 days to complete the work.