Question

A can do a piece of work in 25 days and b can do the same work in 30 days.They work together for 5 days and then A leaves .B will finish the remaining work in how many days?

Answer 1

Answer:

In 1- day A and B can do= 1/20+ 1/25 = 9/100.

In 5- days both can do= 9/100 x 5 =45/100.

Number days required by A to finish the remaining work= (55/100)÷(1/20) = 11- days.

Another method

A does the work till the end and B does the work for 5- days only.

If the total work if finished in X- days, then

So X/20 + 5/25= 1

5X+ 20= 100

X= 80/5= 16.

So complete work is done in 16- days. A alone does after B- left= 16–5= 11- days !!!