A forms a wall in 10 days and B forms it in 15 days. A and B start the work of forming wall together

M4maths Previous Puzzles

20 Jan 2021 Work

A forms a wall in 10 days and B forms it in 15 days. A and B start the work of forming wall together
but after 2 days A leaves the work. How many days are required for making the remaining wall by B?

OPtion

1) 6
2) 9
3) 8
4) 10
5) 12
6) 15
7) 16
8) 20
9) 5
10) None of the above

Solution

One day work of A = 1/10
One day work of B = 1/15
One day work of A and B = 1/10 + 1/15= 1/6
After 2 days of work remaining work = 1- (2*1/6) = 4/6
No. of days required by B for doing this work = (4/6) / (1/15 = 10

Correct Option: 4 Best Solution (2)