# Probability of randomly selected family

Select an American family randomly and count the number of people it contains. Here is the assignment of probabilities for your outcome:

Number of persons: 2 3 4 5 6 7

Probability: 0.42 0.23 0.21 0.09 0.03 0.02

1) What is the probability that the family you choose has more than two people?

2) Using the probabilities above, what is the expected size of the family you draw?

A group of people living together at the same address is a household. Pick one American household at random and record how many people it contains. Here are the probabilities:

Number of persons: 1 2 3 4 5 6 7 or more

Probability: ? 0.32 0.17 0.16 0.07 0.02 0.01

1) What is the probability that the household chosen contains only one person? Or can you tell from the information given?

2) What is the probability that a randomly chosen household contains four or more persons? Or can you tell from the information given?

A store runs a prize game by giving each customer a ticket that may win a prize when scratched. Printed on the ticket are the following probabilities for a customer who shops once a week:

Amount Won Probability

$1000 0.01

$100 0.10

$10 0.20

1) What is the probability of winning nothing?

#### Solution Preview

Number of persons: 2 3 4 5 6 7

Probability: 0.42 0.23 0.21 0.09 0.03 0.02

1) What is the probability that the family you choose has more than two people?

prob = 3 people + 4 people + 5 people + 6 people + 7 people = 0.58

2)Using the probabilities above, what is the expected size of the family ...

#### Solution Summary

Probability a randomly selected family has more than two people; household only one.