Question

A cell phone plan cost $35 per month plus 5 cents for each minute of use. Write a function for the cost of the plan. What are the domain and range of the function?

Answer 1

35 + 0.05 * m

Domain: R +, including 0.

Range: 35 to infinity.

Explanation:

The cell phone plan has a fixed cost of $ 35 and 5 cents per minute, so here comes the variable minutes that we will call m. knowing that 5 cents is 0.05 dollars, then the equation would be:

Total cell plan value = 35 + 0.05 * m

Now to define the domain, it would be the set of possible entries to the equation, that is, in our case, the values that can take m.

Then, the domain would be all positive real numbers, since there can be no negative minutes. Including 0.

Domain: R +, including 0.

Now, the range, on the contrary of the domain, is the set of outputs of a function, in our case the value of the total cell plan.

Therefore in our case, the range would be all real numbers greater than 35, because it is the fixed cost of the plan.

Range: 35 to infinity.