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Can you help me with this math question? it says "A cell phone plan costs $200 to start. Then there is a $50 charge each month, Write an expression that shows the total cost for x months on this plan" Is there a proportional relationship between time and cost of the cell phone plan?

Respuesta :

Cost = 200 + 50x

The relationship between time and cost of the plan is not proportional. By definition, proportional ;relationships between two variables have equivalent ratio; one variable is always a constant value times the other which in this case is not .

To illustrate,

Month 1 Cost = 200 + 50(1) = 250 Ratio ( time:cost) = 1:250

Month2 Cost = 200 + 50(2) = 300 Ratio ( time:cost) = 2:300 = 1:150

Month 3 Cost = 200 + 50(3) = 350 Ratio ( time:cost) = 3:350

Month 4 Cost = 200 + 50(4)= 400 Ratio ( time:cost) = 4 :400 = 1:100

The ratios are not equivalent,thus the relationship is not proportional.

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