Question

A train goes from New Orleans to Boston at 40 mph. On the way back it returns with a speed of 80 mph. If it takes it an hour less time to return, what is its average speed?

Answer 1

Let's say the distance is "x".

time = distance / rate

time1 = x / 40

time2 = x/80

A) time1 shoud be twice time2 or (time1 / time2) =2

B) time1 -1 = time2

Substituting equation B) into A)

((time1 / (time1 -1) = 2

time1 = 2* time1 -2

time1 = 2 hours time2 = 1 hour

Distance = 80 miles

1st trip time1 = 80/40 = 2 hours

return trip time2 = 80/80 = 1 hour

total trip = 160 miles in 3 hours

average speed = 53.333333 miles per hour