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Question 1152212: The cost of driving a car includes both fixed costs and mileage costs. Assume that insurance and car payments cost $360 per month and gasoline, oil, and routine maintenance cost $0.25 per mile.
(a) Find a linear function f that gives the annual cost of driving this car x miles.
(b) What does the y-intercept on the graph of f represent?
Potential Answers:
(a) I initially came up with "f(x) = 0.25x + 360" (.25x represents maintenance, etc. while 360 = fixed cost) *This was initially wrong* It brings up "ANNUAL" cost of driving in the question (I believe is 12 months?)
(b) I believe the y-intercept on the graph is the "Total Cost"
Anything would help greatly!
Thank you.
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website!
(a)
fixed costs = insurance and car payments (these do not change no matter how many miles you drive)
mileage costs = cost of gas, oil, & maintenence (these do change based on how many miles you drive)
x = number of miles
0.25x = cost of driving x miles = mileage costs
360 = monthly fixed cost
360*12 = 4320 = annual fixed cost
f(x) = annual cost of driving x miles
f(x) = (mileage costs) + (annual fixed costs)
f(x) = (0.25x) + (4320)
f(x) = 0.25x+4320
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(b)
The y intercept represents the starting cost, or initial cost. In other words, if you drive x = 0 miles, then the total cost would be $4,320.
Of course you'll likely drive some number of miles, so you'll add on whatever the result of 0.25x would be.
The y intercept is where the graph crosses the y axis.
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