you travel 60 miles at 30mph and it takes 2 hrs to get there, if you travel 90mph on the return how long would it take and what would the average speed be?

Question

find the time it would take on the return trip and then the average speed for the trip there and back combined.

Answer 1

Time for return =  distance/speed

 

                       =60/90

                       =2/3 hours

Total time for going &returning=2+2/3

                                             =8/3 hours

Total distance = 60+60=120 miles

 

Average speed=120/(8/3)

                     =120*3/8

                     =45 mph

 

 

Answer 2

Your trip is 60 miles, if you traveled at 90 mph, r*t=d so 90t = 60, t = 2/3 of an hour or 40 minutes.

 

So your total round trip was 120 miles and it took you 2.666666 hours. r*t=d , r*2.6666666 = 120, r = 45 mph.