A cyclist rides 40 miles in 2 hours, then rides another 45 miles in 1.5 hours. Which value is closest to the cyclist's average speed for…

Average speed is total distance divided by total time: $\frac{40+45}{2+1.5}=\frac{85}{3.5}\approx24.3$ miles per hour, choice G. The speeds on the two legs are $20$ and $30$ mph. Choice H ($25$) averages these two speeds, $\frac{20+30}{2}$, which ignores that the cyclist spent less time at the faster speed. Since more time was spent at $20$ mph, the overall average must be closer to $20$ than to $30$. Choice J ($27.5$) and choice F ($23.0$) do not follow from the total distance and total time.