Question

The monthly cost of a cell phone plan is given by the function C(x) = 0.025x + 35, where x represents the number of minutes

used during the month. Find the number of minutes used during a month when the cost amounted to $47.90.
O 624 minutes
O 574 minutes
O 516 minutes
O 488 minutes

Answer 1

C.) 516 minutes

Explanation:

Let's recall that:

x = number of minutes

C(x) = cost

Since you were given a cost, you can substitute it in for C(x) and simplify the equation to solve for "x".

C(x) = 0.025x + 35 <----- Original equation

47.90 = 0.025x + 35 <----- Plug 47.90 in C(x)

12.90 = 0.025x <----- Subtract 35 from both sides

516 = x <----- Divide both sides by 0.025

As you can see, when the cost was $47.90, the user must have used 516 minutes during the month.