Question 41372
This is a problem from a quiz of mine and I have the answer but I don't know how to get it. Jimmy can only haverage 40 mph when he fights Friday afternoon traffic to drive the 120 miles to his vacation home.
D=120 MILES
S1=40 MPH
T1=D/S=120/40=3 HRS.
 Coming home on Sunday morning, however, he is able to average 60 mph.
S2=60 MPH
T2=120/60=2 HRS.
HENCE FOR ROUND TRIP,WE HAVE
TOTAL DISTANCE TRAVELLED=TD=120+120
TOTAL TIME TAKEN =TT=T1+T2=3+2=5 HRS.
HENCE AVERAGE SPEED =TD/TT=240/5=48 MPH

 What is his average speed for the round trip? Thanks!