Question

Haley pays a monthly fee of $20 for her cell phone and then pays 5 cents per minute used. The cost of Haley’s cell phone bill can be expressed by the function C(m) = 0.05m + 20, where m is the number of minutes used. What are the domain and range of the function C(m)? 

Answer 1

Answer on ED:

A: domain: greater than/ equal to 0

    range: C greater than/ equal to 20

Answer 2

The domain is
{x | x >=0}
Or simply [0, infinity)
Since Haley can not use any negative minutes.

The range is
{y | y >=20}
Or simply [20, infinity)
This is because if Haley doesn't use any minutes, the price will stay at $20.
Let me know if you have any questions.