Chapter 8.5, Problem 67STP

(a)

To determine

The faster car.

Answer to Problem 67STP

Car A.

Explanation of Solution

Given:

The given equations are:

  $\begin{array}{l}\text{Car A = }65mph\\ \text{Car }B\text{ = }60mph.\end{array}$

Calculation:

The Car A has a speed of 65mph and car B has a speed of 60mph. Hence, the car A is having more speed.

(b)

To determine

The expression for the distance between two cars.

Answer to Problem 67STP

  $5t-10$

Explanation of Solution

Given:

The given equations are:

  $\begin{array}{l}\text{Car A = }65mph\\ \text{Car }B\text{ = }60mph.\end{array}$

Calculation:

The solution for the given equation can be obtained as:

  $\begin{array}{l}\text{=(}65t+15)-(60t+25)\\ =65t+15-60t-25\\ =5t-10\end{array}$

(c)

To determine

The distance between the cars after 2.5 hours.

Answer to Problem 67STP

  $2.5\text{ miles} \text{apart}$

Explanation of Solution

Given:

The given equations are:

  $\begin{array}{l}\text{Car A = }65mph\\ \text{Car }B\text{ = }60mph.\end{array}$

Calculation:

Substituting 2.5 for t,

  $\begin{array}{l}=5t-10\\ =5(2\frac{1}{2})-10\\ =\frac{25}{2}-\frac{20}{2}\\ =\frac{5}{2}\\ =2.5\end{array}$

After 2.5 hours, the cars will be 2.5 miles apart.