# Probability based on a Random Sample

Three in five adults in the U.S. own an answering machine. In a random sample of 12 adults, what is the probability that the number owning answering machine is:

A) exactly nine,

B) at least nine,

C) What is the expected value of the random variable defined in this problem?

https://brainmass.com/statistics/probability/probability-based-random-sample-430751

#### Solution Preview

Let X be the number out of 12 adults that own an answering machine. Based on the information given by the problem, X ~ binomial(12, 3/5) = binomial(12, 0.6)

For a ...

#### Solution Summary

This solution shows how to calculate the given probability questions.

$2.19