The problem describes the constraints on a student's work hours and earnings at a college. Students can work no more than 20 hours per week and can earn a maximum of $320 per week. The jobs pay different rates, starting from $8.75 per hour. We need to write two inequalities representing these constraints and define the variables used.
2025/3/25
1. Problem Description
The problem describes the constraints on a student's work hours and earnings at a college. Students can work no more than 20 hours per week and can earn a maximum of 8.75 per hour. We need to write two inequalities representing these constraints and define the variables used.
2. Solution Steps
Let represent the number of hours a student works per week.
Let represent the amount a student earns per week.
The first constraint is that the student can work no more than 20 hours per week. This can be represented by the inequality:
The second constraint is that the student can earn a maximum of $320 per week. This can be represented by the inequality:
However, since the minimum rate is ehe \le 3208.75$, we can have the following inequality:
. This implies that
Dividing both sides by 8.75, we have:
However, we are already given that , which is stricter than , so we use .
The amount a student earns depends on the hourly rate multiplied by the number of hours worked. Let be the rate earned per hour.
Then . Since the hourly rate is at least r \ge 8.75$.
Also, the earnings are at most e \le 320$.
A valid inequality to represent the income is: . If we divide both sides by 8.75, we get:
.
However, we also have the constraint that . So a better inequality is:
, and . Therefore, we can say that .
Since , the maximum income should be .
The two inequalities are and .
Alternatively, we can also use , if the rate is fixed at h_iir_ii\sum h_i \le 20\sum r_i h_i \le 320r_i8.75\sum 8.75 h_i = 8.75 \sum h_i \le 320$.
Since , .
3. Final Answer
The two inequalities are:
where represents the number of hours a student works per week and represents the amount a student earns per week.