Q:

Two pipes P and Q would fill a cistern in 24 hours and 32 hours respectively. If both pipes are opened together, find when the pipe “P” must be turned off so that the cistern may be just filled in 16 hours-

• 1
  After 8 hrs
• 2
  After 12 hrs
• 3
  After 14 hrs
• 4
  After 16 hrs