Question

The following is the cost function for natural gas for the city where Greg lives. Greg's natural gas bill last month was $51.54. How many therms did Greg use last month? Round the answer to the nearest tenth of a therm (one decimal place). Only input the number. Do not input any unit. Example: 89.3

Answer 1

Kauro, this is the solution:

This is the cost function for natural gas for the city where Greg lives:

• c (t) = 16.74 + 0.742t

Now we replace c (t) by 51.54 to solve for t, as follows:

51.54 = 16.74 + 0.742t

Subtracting 16.74 at both sides:

51.54 - 16.74 = 16.74 + 0.742t - 16.74

34.8 = 0.742t

Dividing by 0.742 at both sides:

0.742t/0.742 = 34.8/0.742

t = 46.9 therms

The correct answer is 46.9