Question

a cyclist rides at an average speed of 21 mi/h. if the cyclist wants to bike 169 km, how long (in hours) must they ride? express your answer in hours to two significant figures. time = h

Explanation:

Step1: Convert kilometers to miles

1 mile is approximately 1.60934 km. So, $169\ km\times\frac{1\ mi}{1.60934\ km}\approx105\ mi$.

Step2: Use the speed - time formula

The formula for time $t$ is $t = \frac{d}{v}$, where $d$ is distance and $v$ is speed. Given $v = 21\ mi/h$ and $d\approx105\ mi$, then $t=\frac{105\ mi}{21\ mi/h}= 5.0\ h$.

Answer:

$5.0$