Question

A telephone plan consists of a monthly fee of $25 plus 25 cents per minute for long distance calls made. Write an equation for the total monthly cost C when n minutes are used for long distance callsGraph the equationestimate monthly cost if 50 min of long distance calls are made Find out if the total monthly bill is $35 estimate the number of mins used for long distance calls.

Answer 1

(a)C=25+0.25n

(b)Graph A

(c)$37.50

(d)40 minutes

Step-by-step explanation:

Part A

Monthly Fee = $25

Cost per minute = 25 cents = $0.25

Therefore, an equation for the total monthly cost C when n minutes are used is:

`C=25+0.25n`

Part B

The equation C=25+0.25n has the following properties:

• Rate of change = 0.25

,

• y-intercept = 25

From the given graphs, the one that satisfies these properties is Graph A shown below:

Part C

If 50 min of long-distance calls is made, the estimated monthly cost is circled in red above.

• Trace it to the y-axis

,

• It is halfway between 35 and 40.

`\begin{gathered} 35+(5)/(2)=35+2.50 \\ =\$37.50 \end{gathered}`

The estimated monthly cost for 50 mins of long-distance calls is $37.50.

Part D

If the total monthly bill is $35

From the graph, trace the point circled in green to the x-axis.

The number of mins used for long-distance calls is 40 minutes.