Probability (rock) :
78 / 150 = 13/25 = 52%
Rock is preferred by 52% of the 150 visitors that were surveyed
To find how many people will likely sell from the rock genre, you need to find 52% of the estimated sales (6,000 copies).
52% • 6000 = 3,120
Answer: C. 3,120
Second one...................
First of all, a positive average rate of change means that the function is increasing, so the answer can only be A->B or B->C.
The average rate of change is defined as

i.e. as the ratio between the vertical and horizontal gain.
In order to go from point A to point B, you gain 1 unit horizontally and 5 units vertically. So, the average rate of change is 5/1=5.
In order to go from point B to point C, you gain 1 unit horizontally and 3 units vertically. So, the average rate of change is 3/1=3.
Answer:
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