#4 is 47, 48, 49
47+48+49=144
<h3>
Answer: 78.6</h3>
Work Shown:

Multiply across the rows to form a third column. Example: 9*90 = 810 in the first row.

The values in the third column add to 810+1440+1050 = 3300
Divide this over the total number of people which is 9+18+15 = 42
The mean is 3300/42 =78.571 approximately which rounds to 78.6
Answer:
$12 per hour
Step-by-step explanation:
In order to find her hourly rate we have to find the amount of dollars billed per hour. To do this we can use this expression: 
Let's use the points (1, 27) and (2, 39) in the expression:

Now let's simplify the expression:
39 - 27 = 12
2 - 1 = 1
The expression simplifies to 12/1, or 12. This means that Brenda is billed $12 every hour she uses her phone.
I hope this helps :)