Question

A survey of Us adults found 41% have encountered frandudent charges on thier credit cards
imagine your sample 30 people at random from this population.

1) about what is the expected mean and standard deviation of the sample ?

2) about what is likelyhood that 3 or fewer have have fraudulent charges on thier credit cards?

3) about what is the likelihood 5 or greater have had fraudulent charges on thier credit cards?

4) about what is the likelihood that exactly 4 have had fraudulent charges on thier credit cards?

Answer 1

Let X is a random variable shows the number of people had fraudulent charges on their credit cards. Here X has binomial distribution with parameters n=30 and p=0.41.

(a)

The mean is

The standard deviation is

(b)

The likelihood that 3 or fewer have had fraudulent charges on their credit cards is

(c)

The likelihood that 5 or greater have had fraudulent charges on their credit cards is

(d)

The  likelihood that exactly 4 have had fraudulent charges on their credit cards is