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.
PLEASE HELP!!

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

Is not a very difficult question

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