Creating a Piecewise Function - Cell Phone Plan

Question

Anna's phone plan charges $15 monthy for the first 110 international minutes and the $2 a minute for every minute over the first 110.

Create a piecewise function that defines the price of Anna's monthly cell phone bill in terms of the number of international minutes used.

Answer 1

C = cost/mo. M = no. minutes/mo.

For M ≤ 110 C = 15

For M > 110 C = 15 + 2(M - 110) So there's an additional $2 chrg for every minute in excess of 110.

.

For 120 min. used in a month, cost would be 15 + 2(120 -110) -> 15 + 2(10) -> 15 + 20 = $35, $15 for the 1st 110 min. plus $2 for each of the extra 10 min.