Answer:
We need to send more than 400 messages for Plan B to be the better option.
Step-by-step explanation:
Plan A
The cost is a flat fee of 30 plus 10 cents per message
Cost= 30 +.10m
Plan B
The cost is a flat fee of 50 plus 5 cents per message
Cost = 50 +.05m
We want cost of B to be less than cost A
30 +.10m > 50 +.05m
Subtract .05m from each side
30 +.10m- .05m > 50 +.05m-.05m
30 +.05m > 50
Subtract 30 from each side
30-30 +.05m > 50-30
.05m > 20
Divide each side by .05
.05/.05m > 20/.05
m > 400
We need to send more than 400 messages for Plan B to be the better option.
Answer:
120
Step-by-step explanation:
We are given that the function for the number of students enrolled in a new course is
.
It is asked to find the average increase in the number of students enrolled per hour between 2 to 4 hours.
We know that the average rate of change is given by,
,
where f(x)-f(a) is the change in the function as the input value (x-a) changes.
Now, the number of students enrolled at 4 = f(4) =
= 255 and the number of students enrolled at 2 = f(2) =
= 15
So, the average increase
=
=
= 120.
Hence, the average increase in the number of students enrolled is 120.