A telephone company offers a monthly cellular phone plan for \[tex]$19.99. It includes 350 anytime minutes plus \$[/tex]0.20 per minute for additional minutes. The following function is used to compute the monthly cost for a subscriber, where [tex]\( x \)[/tex] is the number of anytime minutes used:

[tex]\[ C(x) = \begin{cases}
19.99 & \text{if } 0 \ \textless \ x \leq 350 \\
0.20x - 50.01 & \text{if } x \ \textgreater \ 350
\end{cases} \][/tex]

Compute the monthly cost of the cellular phone for the following anytime minutes:

(a) 215
(b) 410
(c) 351

(a) [tex]\( C(215) = \$19.99 \)[/tex] (Round to the nearest cent as needed.)
(b) [tex]\( C(410) = \$ \square \)[/tex] (Round to the nearest cent as needed.)
(c) [tex]\( C(351) = \$ \square \)[/tex] (Round to the nearest cent as needed.)



Answer :

Certainly! Let's go through each part step-by-step to compute the monthly cost for the given anytime minutes used, using the given cost function:

### Given Cost Function
[tex]\[ C(x) = \begin{cases} 19.99 & \text{if } 0 < x \leq 350 \\ 0.20x - 50.01 & \text{if } x > 350 \end{cases} \][/tex]

### Part (a): Compute [tex]\(C(215)\)[/tex]

For [tex]\(x = 215\)[/tex]:
1. Since [tex]\(215\)[/tex] falls in the range [tex]\(0 < x \leq 350\)[/tex],
2. We use the cost function [tex]\(C(x) = 19.99\)[/tex].

Thus, [tex]\(C(215) = 19.99\)[/tex].

### Part (b): Compute [tex]\(C(410)\)[/tex]

For [tex]\(x = 410\)[/tex]:
1. Since [tex]\(410\)[/tex] falls in the range [tex]\(x > 350\)[/tex],
2. We use the cost function [tex]\(C(x) = 0.20x - 50.01\)[/tex].

Substitute [tex]\(x = 410\)[/tex]:

[tex]\[ C(410) = 0.20 \times 410 - 50.01 \][/tex]

[tex]\[ C(410) = 82.00 - 50.01 \][/tex]

[tex]\[ C(410) = 31.99 \][/tex]

Thus, [tex]\(C(410) = 31.99\)[/tex].

### Part (c): Compute [tex]\(C(351)\)[/tex]

For [tex]\(x = 351\)[/tex]:
1. Since [tex]\(351\)[/tex] falls in the range [tex]\(x > 350\)[/tex],
2. We use the cost function [tex]\(C(x) = 0.20x - 50.01\)[/tex].

Substitute [tex]\(x = 351\)[/tex]:

[tex]\[ C(351) = 0.20 \times 351 - 50.01 \][/tex]

[tex]\[ C(351) = 70.20 - 50.01 \][/tex]

[tex]\[ C(351) = 20.19 \][/tex]

Thus, [tex]\(C(351) = 20.19\)[/tex].

### Summary of Results

- [tex]\(C(215) = 19.99\)[/tex]
- [tex]\(C(410) = 31.99\)[/tex]
- [tex]\(C(351) = 20.19\)[/tex]

Each cost is rounded to the nearest cent as specified.