Question 980522
A train goes from New Orleans to Boston at 40 mph. On the way back it returns with a speed of 80 miles per hour. If it takes less time to return, what is it's [sic] average speed?
===================
If it takes less time... ?  It's going 2x as fast, takes half as long, no if about it.
===============
Avg speed of a round trip = 2*r1*r2/(r1+r2)
= 2*40*80/(120)
= 160/3 mi/hr
= 53.33 mi/hr
==================
it's = it is