The cost C of joining FitFast Gym includes an initial membership fee of $127, plus a monthly fee, m, of $28.

Question

a. The cost of going to the gym is a function of the number of months of membership. Find a rule for the function.
b. Find the cost of using the gym for 9 months.
c. Graph the function.
A. a. C = 34m + 77
b. $379
c.
graphThe horizontal axis extends from 0 to 11 and is labeled 'Time (months).' The vertical axis extends from 0 to 500 and is labeled 'Cost ($).' On the left, the graph begins at the point 0 comma 90. The graph follows a line up and to the right through the point 11 comma 450.
B. a. C = 28m + 127
b. $379
c.
graphThe horizontal axis extends from 0 to 12 and is labeled 'Time (months).' The vertical axis extends from 0 to 500 and is labeled 'Cost ($).' On the left, the graph begins at the point 0 comma 140. The graph follows a line up and to the right through the point 8 comma 350.

C. a. C = 28m + 117
b. $369
c.
graphThe horizontal axis extends from 0 to 12 and is labeled 'Time (months).' The vertical axis extends from 0 to 500 and is labeled 'Cost ($).' On the left, the graph begins at the point 0 comma 120. The graph follows a line up and to the right through the point 12 comma 450.

D. a. C = –28m + 227
b. $53
c.
graphThe horizontal axis extends from 0 to 12 and is labeled 'Time (months).' The vertical axis extends from 0 to 500 and is labeled 'Cost ($).' On the left, the graph begins at the point 0 comma 230. The graph follows a line down and to the right through the point 8 comma 0.

Answer 1

The correct answer is option B:

a. C = 28m + 127 (Cost function is a linear equation with slope $28 and y-intercept $127)
b. $379 (Substitute m = 9 in the cost function: C = 28(9) + 127 = $379)
c. Graph: