Question

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?

Answer 1

15,040(1.21)t ≤ 100,000

Explanation:

got it right

Answer 2

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