What is the expected percentage of people responding to an advertisement when the probability distribution is the one given in problem 3–3? What is the variance of the percentage of people who respond to the advertisement?

problem 3–3

The percentage of people (to the nearest 10) responding to an advertisement is a random variable with the following probability distribution

a. Show that P(x) is a probability distribution.

b. Find the cumulative distribution function.

c. Find the probability that more than 20% will respond to the ad