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29 votes
29 votes
You work no more than 12 hours a week at your two jobs. The first job pays you $8 an hour, and the second job pays you $10 an hour. You must earn at least $100 each week. Which graph represents this situation (let x represent hours at job 1 and y represent hours at job 2)?

A. none

You work no more than 12 hours a week at your two jobs. The first job pays you $8 an-example-1
You work no more than 12 hours a week at your two jobs. The first job pays you $8 an-example-1
You work no more than 12 hours a week at your two jobs. The first job pays you $8 an-example-2
You work no more than 12 hours a week at your two jobs. The first job pays you $8 an-example-3
User Matthew Grima
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1 Answer

16 votes
16 votes

Answer:

the third picture

Explanation:

You work x hours at the first job and y hours at the second. The total amount of hours must be less than or equal to 12 because you work no more than 12 hours a week (but can work exactly 12 hours a week). As x+y represents the amount of hours worked per week , we can represent this inequality as

x + y ≤ 12

Next, you must earn more than (or equal to) $100 each week. As you get $8 each hour for the first job, the amount of money you get for the first job each week can be represented as 8 * x. Similarly, the amount of money you get from the second job can be represented as 10 * y, and the total amount of money you get can be shown as

8 * x + 10 * y

This is greater than or equal to 100, so

8 * x + 10 * y ≥ 100

We therefore have

x + y ≤ 12

8 * x + 10 * y ≥ 100

One relatively simple way to solve this is to take into account that both inequalities have an equals in them (less than or equal to or greater than or equal to). Therefore, there are no dotted lines. One inequality is less than or equal to, and one inequality is greater than or equal to, so the shaded area must be lower than one line and greater than the other. The only one that fits this is the third picture.

To really make sure this is correct, we can first confirm that the lines correspond to x + y = 12 and 8 * x + 10 * y = 100 by plugging values in. For example, for the line that starts higher on the left side, we can see that we have points at (0, 12) and (12,0). In both of these cases, x+y=12. In our inequality, x + y ≤ 12 , so the shaded area must be under that line. We can also confirm that 8 * x + 10 * y = 100 is the other line by taking in two points ((0,10) and (12.5,0) for example) and plugging them in. We know that 8 * x + 10 * y ≥ 100, so this must be above the line that starts lower on the left side. Therefore, the shaded area must be between the two lines and not dotted (not dotted because both inequalities have an equals in them), which fits with the third picture

User Vanddel
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