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

Yes, it would be 53.33 miles per hour!

Distance from New Orleans to Boston and back is the same.

t - time from New Orleans to Boston

(t-1) - time from Boston to New Orleans

40t - distance between New Orleans and Boston.

80 (t-1) - distance between Boston and New Orleans.

40t = 80 (t-1)

40t = 80t - 80

40t = 80

t=2 h

To find average speed we need to find all distance and divide it at all time.

All distance = 40t + 80 (t-1) = 120t - 80

All time = t + (t-1) = 2t-1

Average speed = (120t - 80) / (2t-1)

Now we can substitute t=2.

Average speed = (120*2 - 80) / (2*2-1) = 53.33 m/s