Chapter 4.10, Problem 13P

To determine

the speed of the bus for the rest of the trip to keep on schedule.

Answer to Problem 13P

  $52\text{mi/h}$

Explanation of Solution

Given:

Speed of the bus driven for $5\text{h}$ is $49\text{mi/h}$ .

Speed of the bus for $1.5\text{h}$ is $42\text{mi/h}$ .

Calculation:

Total distance covered by bus for $5\text{h}$ journey is .

  $\begin{array}{l}s=\text{Speed×Time}\\ s=49\text{×5}\\ s=245\text{mi}\end{array}$

Distance covered in first $1.5\text{h}$ is.

  $\begin{array}{l}=42\times 1.5\\ =63\text{mi}\end{array}$

Remaining distance.

  $\begin{array}{l}=245-63\\ =182\text{mi}\end{array}$

Remaining time.

  $\begin{array}{l}=5-1.5\\ =3.5\text{h}\end{array}$

Speed of the bus for the rest of the trip to keep on schedule.

  $\begin{array}{l}=\frac{182}{3.5}\\ =52\text{mi/h}\end{array}$

Therefore, the answer $52\text{mi/h}$ .