A box contains a yellow ball, an orange ball, a green ball, and a blue ball. Billy randomly selects 4 balls from the box (with replacement). What is the expected value for the number of distinct colored balls Billy will select?

Step-by-step explanation:

Given

--- selection

Required

The expected distinct colored balls

The probability of selecting one of the 4 balls is:

The probability of selecting different balls in each selection is:

Substitute 4 for n

The number of arrangement of the 4 balls is:

So, we have:

The expected number of distinct color is:

Y is directly proportional to x. If y=30 and x=6, find the value of k (the constant.) Divide both y and x by x. Then you shall get the value of k, which is, in this case, 5. SO the answer is A: She could divide and y-value by its corresponding x-value.