A alone would take 4 hours more to complete a job than both A and B would together. If B worked alon

M4maths Previous Puzzles

25 Jan 2022 Time and Work

A alone would take 4 hours more to complete a job than both A and B would together. If B worked alone, he took 9 hours more to complete it than both A and B worked together. What time (in hrs) would they take if both worked together?

OPtion

1) 12
2) 10
3) 14
4) 8
5) 9
6) 5
7) 7
8) 6
9) 7.5
10) None of these

Solution

Let time taken by A and B together be 't' hours
Thus, time taken by A = (t+4) hrs and time taken by B = (t+9) hrs
Now, equating work done by A and B in 1 hour:
1/(t+4) + 1/(t+9) = 1/t
Solving, we get, t=6 hours.

Correct Option: 8 Best Solution (1)