Power usage is measured in kilowatt-hours, kWh. After 7 a. m., the power usage on a college campus increases at a rate of 21% per hour. Prior to 7 a. m., 15,040 kWh have been used. The university has a daily goal to keep their power usage less than or equal to 100,000 kWh. Which of the following inequalities can be used to determine the number of hours, t, after 7 a. m. when the power usage on campus will be less than or equal to 100,000?

After 7 a. m., the power usage on a college campus increases at a rate of 21% per hour.

t be the number of hours

the power usage increases at a rate of 21% per hour

21% = 0.21, constant rate = 0.21. So slope = 0.21

Prior to 7 a. m., 15,040 kWh have been used.

At 7. am, power used = 15,040kWh. so our y intercept is 15,040

We use slope intercept form y=mx+b

slope m = 0.21 and b = 15040

power usage, y = 0.21 t + 15040

The university has a daily goal to keep their power usage less than or equal to 100,000 kWh

Power usage is less than or equal to 100,000

So inequality becomes 0.21t + 15,040 < = 100,000

15,040 (1.21) t ≤ 100,000

Step-by-step explanation:

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