Explanation:
Let the distance from A to B be s.
A car travels from A to B at a speed of 40 mph then returns, using the same road, from B to A at a speed of 60 mph.
[tex]\texttt{Time taken to travel from A to B = }\frac{s}{40}\\\\\texttt{Time taken to travel from B to A = }\frac{s}{60}\\\\\texttt{Total time = }\frac{s}{40}+\frac{s}{60}\\\\\texttt{Total time = }\frac{60s+40s}{40\times 60}\\\\\texttt{Total time = }\frac{100s}{2400}\\\\\texttt{Total time = }\frac{s}{24}[/tex]
Total distance traveled = 2s
Total distance traveled = Average speed x Total time
[tex]2s=\texttt{Average speed}\times \frac{s}{24}\\\\\texttt{Average speed = }48mph[/tex]
Average speed of round trip is 48 mph
