P and Q can fill a water tank in 9hr and 12 hr respectively but R can
Right Answer is: C
Total capacity of tank = 36 units
Net efficiency of P, Q and R = 4+3 -2 = 5
Pipe P starts at 2 PM.
Tank filled by pipe P in 2 hrs = units
Pipe Q starts at 3 PM.
Water tank filled by pipe Q in 1 hr = units
Total water tank filled in 2 hr = 8 +3 = 11 units
Empty tank = 36 units – 11 units = 25 units
Time taken to fill the empty tank =
Hence tank will be completely filled at 9 PM