Question

According a study, 15 percent of adults in Canada do not use Internet. Suppose that 10 adults are randomly selected.

a.     What is the probability that 3 of the adults do not use the Internet?

b.     What is the probability that at least 3 of the adults do not use the Internet?

c.     Now suppose that 200 adults are randomly selected. What is the probability that at least 180 adults use Internet?

Please show your work and thank you SO much in advance! You are helping a struggling stats student SO much!

Answer 1

Here p=0.15 which is same for all, n=10 is constant

Events are independent and only two outcomes

Hence all the properties of binomial are satisfied

So we will use excel formula of binomial to find required probabilty

a.

b.

c. Now as n is large we will use normal approximation (here p=0.85)

and standard deviation is

Now we need to find

As we can use normal approximation we can convert x to z

So are the answers