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Question 994439: A phone company has a monthly cellular data plan where a customer pays a flat monthly fee of $10 and then a certain amount of money per megabyte (MB) of data used on the phone. If a customer uses 20 MB, the monthly cost will be $11.20. If the customer uses 130 MB, the monthly cost will be $17.80.
A. Find a linear equation for the monthly cost of the data plan as a function of x, the number of MB used.
B. Interpret the slope and vertical intercept of the equation.
C. Use your equation to find the total monthly cost if 250 MB are used.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A phone company has a monthly cellular data plan where a customer pays a flat monthly fee of $10 and then a certain amount of money per megabyte (MB) of data used on the phone. If a customer uses 20 MB, the monthly cost will be $11.20. If the customer uses 130 MB, the monthly cost will be $17.80.
A. Find a linear equation for the monthly cost of the data plan as a function of x, the number of MB used.
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You are given 2 points:: (20,10,21.20) ; (130,27.80)
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slope = (27.8-21.2)/(110) = 0.06
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Cost = 0.06x + b
Solve for "b"
21.20 = 0.06*20 + b
21.2 = 1.2 + b
b = 20
Cost = 0.06x + 20
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B. Interpret the slope and vertical intercept of the equation.
slope = 0.60 means $0.06 or 6 cents extra for each MB over 20
intercept = $20 for joining the plan and using less than 20 MB
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C. Use your equation to find the total monthly cost if 250 MB are used.
250-20 = 230 MB
C(230) = 0.06*230 + 20 = $33.80
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Cheers,
Stan H.
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