saumya17lc wrote:
It takes Joey the postman 1 hours to run a 3 mile long route every day. He delivers packages and then returns to the post office along the same path. If the average speed of the round trip is 5 mile/hour, what is the speed with which Joey returns?
11
12
13
14
15
The answer is in minutes..while the question asks for speed..Please clarify..because if its is speed that is being asked the answer should probably me 15 and if time is being asked the answer is 12
The answer has to be 15 mile and not 12 mile-
Av speed= 5 mile
S1 speed for 1st half of the journey
S2 speed for return voyage
therefore Av speed = 2*S1*S2/(S1+S2)
ie 5= 2*3*S2/3+S2.
Solving for S2 = 15 mile