Consider two postmen A and B respectively. A is young and can deliver 20 parcels in 3 hours while B is older than A and can deliver only 15 parcels in 4 hours. If the total number of parcels to deliver is 60, how long they will take working together.

a. 121/12 hours b. 144/36 hours c. 144/25 hours d. 121/25 hours

• work done by 1st = 20/3 , work done by 2nd = 15/4 (here work is work/hour)
  total work done together = 20/3+15/4 =125/12
  time to do 60 unit work(ie, parcels)= 60*12/125 = 144/25 S0, ans. is c.
• 13 years agoHelpfull: Yes(26) No(0)
• 1st postman in 1 hr work done=20/3
  2nd postman in 1 hr work done=15/4
  if they work together ,in 1 hr they work done=20/3+15/4=125/12
  so,time require to deliver 60 parcel=12*60/125=144/25
• 13 years agoHelpfull: Yes(1) No(0)