Question

Starting at 48th Street, Dylan rides his bike due east on Meridian Road with the wind at his back. He rides for 20 min at 15 mph. He then stops for 5 min, turns around, and rides back to 48th Street; because of the headwind, his speed is only 10 mph.

Answer 1

Answer:

55 min

Explanation:

The missing question is: how long does the trip take?

First of all, we need to find the initial distance covered by Dylan. In the first part, he rides for

$t_1 = 20 min = \frac{1}{3}h$

at a speed of

v = 15 mph

therefore, the distance he covered is

$d = v t_1 = (15)(\frac{1}{3})=5 mi$

Then Dylan stopped for a time of

$t_2 = 5 min = \frac{5}{60}=\frac{1}{12}h$

Finally, on the way back, Dylan covered again this distance but travelling at a new speed of

v = 10 mph

So, the time he took is

$t_3 = \frac{d}{v}=\frac{5}{10}=\frac{1}{2}h = 30 min$

So, the total time of the trip was

$t=t_1 + t_2 + t_3 = 20 min + 5 min + 30 min = 55 min$