Question

The phone company NextFell has a monthly cellular plan where a customer pays a flat monthly fee and then a certain amount of money per minute used on the phone. If a customer uses 260 minutes, the monthly cost will be $114. If the customer uses 640 minutes, the monthly cost will be $247.

A) Find an equation in the form y= mx+b, where x is the number of monthly minutes used y is the total monthly cost of the NextFell plan.


Answer: _____



B) Use your equation to find the total monthly cost if 949 minutes are used.


Answer: If 949 minutes are used, the total cost will be _____ dollars.

Answer 1

Explained below.

Explanation:

(A)

Use two-point form to determine the equation for the total monthly cost of the NextFell plan.

`(y-y_(1))=(y_(2)-y_(1))/(x_(2)-x_(1))\cdot (x -x_(1))\\\\(y-247)=(247-114)/(640-260)\cdot (x-640)\\\\(y-247)=0.35x-224\\\\y=0.35x+23`

(B)

Compute the total monthly cost if 949 minutes are used as follows:

`y=0.35x+23\\\\=(0.35* 949)+23\\\\=355.15`

Thus. the total monthly cost if 949 minutes are used is $355.15.