Question

Two cell phone companies charge a flat fee plus an added cost for each minute or part of a minute used. The cost is represented by C and the number of minutes is represented by t.
Call-More: C = 0.40t + 25
Talk-Now: C = 0.15t + 40

a) Which company is cheaper if a customer talks for 50 minutes?


b) Under what conditions do the two companies charge the same?

Answer 1

Answer:

a) Call-more is cheaper

b) 60 minutes

Step-by-step explanation:

Call-More: C = 0.40t + 25

Talk-Now:  C = 0.15t + 40

a) Substitute t =  50 minutes in the above equations.

Call-More:

         C = 0.40*50 + 25

            = 20 + 25

        C = 45

 Talk-Now:

          C = 0.15*50 + 40

              = 7.5 + 40

          C  = 47.40

Company Call-more is cheaper than Talk-now.

b) We have to find the conditions under what condition the two companies charge the same.

    Charge of company Call-more = charge of company Talk-now.

                  0.40t + 25 = 0.15t + 40

                            0.40t = 0.15t + 40 -25

                            0.40t = 0.15t + 15

                 0.40t - 0.15t = 15

                             0.25t = 15

                                     $\sf t = \dfrac{15}{0.25}\\\\ t = \dfrac{15*100}{25}$

                                     t = 15*4

                                     t = 60 minutes

Two companies charge the same for 60 minutes.