A cyclist travels the first 30 km at 20 km/h, the next 50 km at 25 km/h, and the final 20 km at 10 km/h. What is the cyclist's average speed for the entire 100 km trip (round off to the nearest integer)?
18 km/h
Average speed equals total distance divided by total time.
Time for first leg: \(t_1 = \dfrac{30}{20} = 1.5\) hours.
Time for second leg: \(t_2 = \dfrac{50}{25} = 2\) hours.
Time for third leg: \(t_3 = \dfrac{20}{10} = 2\) hours.
Total time: \(T = 1.5 + 2 + 2 = 5.5\) hours.
Average speed: \(\dfrac{100}{5.5} \approx 18.18\) km/h.
Hence, the average speed rounded to the nearest integer is 18 km/h.
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