Correct Answer - Option 4 : 12 hours
Given:
P and Q can fill a tank = 6 hours
R can empty fill a tank = 4 hours
Formula Used:
Work done = Total work/Total work done in 1 hour
Calculation:
Taps
|
Work can be complete in days
|
LCM of 6 and 4
|
Work done by tap in 1 hour
|
P + Q
|
6
|
12
|
2
|
R
|
4
|
|
-3
|
Total work done in an hour
|
|
|
-1
|
Work done = Total work/Total work done 1 hour by all three
⇒ Work done by (P + Q + R) = 12/(-1) = 12 hours
∴ Work done by P, Q and R in 12 hours.
The correct option is 4 i.e. 12 hours