Answer:
It cost $30 to talk for 8 hours and $66 to talk for 20 hours.
Step-by-step explanation:
We are given the following information in the question:
Cost C in dollars is given by a linear function:
[tex]C(t) = 6 + 0.05t[/tex], where t is the number of minutes talked.
a) Total cost f talking for 8 hours
1 hour = 60 minutes
8 hours = 480 minutes
20 hours = 1200 minutes
Putting t = 480 in the given cost function,
[tex]C(480) = 6 + 0.05\times 480 = 30[/tex]
Putting t = 1200 in the given cost function,
[tex]C(1200) = 6 + 0.05\times 1200 = 66[/tex]
Thus, it cost $30 to talk for 8 hours and $66 to talk for 20 hours.
b)
[tex]\text{Effective cost per minute} = \displaystyle\frac{\text{Total cost}}{\text{Number of minutes}}[/tex]
[tex]\text{Effective cost of talking for 8 hours} = \displaystyle\frac{30}{480} = 0.0625[/tex]
[tex]\text{Effective cost of talking for 20 hours} = \displaystyle\frac{66}{1200} = 0.055[/tex]
