Question

In May 2003, JP Gas Co. had the following rate schedule for natural gas usage in single-family residences. Gas is

measured in units called therms. All customers pay a monthly charge. They also pay a distribution charge based on
the amount of gas they use and a supply charge that is also based on the amount of gas they use. The fees are as
follows:
Monthly Customer Charge $6.45
Distribution Charge
1st 20 therms $0.20/therm
Next 30 therms $0.11/therm
Over 50 therms $0.04/therm
Gas supply charge $0.73/therm
a) What is the charge for using 40 therms?
b) What is the charge for using 202 therms?
c) Construct a function that gives the monthly charge C for the x therms of gas.

Answer 1

a) $40.05

b) $161.99

c) C(x) = 6.45 + 0.93x, if x ≤ 20

C(x) = 6.45 + 0.84x, if x > 20 and x ≤ 50

C(x) = 6.45 + 0.77x if x > 50