Chapter 8, Problem 59CR

To determine

How many cars must he shell monthly to earn at least $4500

Answer to Problem 59CR

The salesman must sell a minumum number s of cars to earn at least $4500 is $20$

Explanation of Solution

Given:

A car sales associate recieves a monthly salary of $1700 a month plus $140 for every car he sell and total he earn is $4500

Concept Used:

• If there is the strict inequality symbol $<\text{ or}>$ , then use a parenthesis $\left(\right)$ on the interval
• If there is the inequality symbol $\le \text{ or}\ge$ , then use a bracket $\left[\right]$ on the interval

Calculation:

In order to find the enquality. Let x be the number of cars sol . The salesman’s monthly income is equal to his monthly salary plus the product of the number of cars sold and the bounus per car sold as below:

  $\begin{array}{c}4500\le 1700+140x\\ 4500-1700\le 1700+140x-1700\\ 2800\le 140x\\ \frac{2800}{140}\le \frac{140x}{140}\\ 20\le x\end{array}$

Thus, the salesman must sell a minumum number s of cars to earn at least $4500 is $20$