Chapter 2.6, Problem 15P

Car 1 drove 408 miles in 6 hours and Car 2 drove 365 miles in 5 hours during the cross-country road race. Who had the fastest average speed?

To determine

To Find: The car has the fastest average speed.

Answer to Problem 15P

Car 2 has the fastest average speed.

Explanation of Solution

Given:

Distance travelled by 1^st car in $6\text{h}$ is $408\text{mi}$

Distance travelled by 2^nd car in $5\text{h}$ is $365\text{mi}$

Formula used:

Average speed can be given as:

  $\text{average speed =}\frac{\text{distance travelled}}{\text{total time taken}}$

Calculation:

Average speed of car 1 is:

  $\begin{array}{l}{\left(\text{average speed }\right)}_{car1}\text{=}\frac{\text{408 mi}}{\text{6 h}}\\ {\left(\text{average speed }\right)}_{car1}\text{=}68\text{mi/h}\end{array}$

Average speed of car 2 is:

  $\begin{array}{l}{\left(\text{average speed }\right)}_{car2}\text{=}\frac{\text{365 mi}}{\text{5 h}}\\ {\left(\text{average speed }\right)}_{car2}\text{=}73\text{mi/h}\end{array}$

On comparing both the speeds,

The fastest average speed is of car 2

i.e. $73\text{mi/h}$