# Calculating probabilities.

1) The odds of the Dallas Cowboys winning this year's Super Bowl are 3 to 1. Compute the probability of the Cowboys winning a).33 b).25 c).75 d) none.

2) An appliance dealer calculated the proportion of new dishwashers sold that required various numbers of service calls to correct problems during the warranty period. The records were:

No. of Service calls Relative frequency

0 0.25

1 0.38

2 0.30

3 0.04

4 0.03

Let X be the number of service calls during the warranty period for a dishwasher.

What is the probability that there will be between two and four (inclusive) service calls? a) .34 b).07 c).04 d).37

3) The table below gives the probabilities of combinations of religion and political parties in a major U.S. city.

Religion

Political Parties Protestant(A) Catholic(B) Jewish(C) Other(D)

Democrat (E) 0.35 0.10 0.03 0.02

Republican (F) 0.27 0.09 0.02 0.01

Independent (G) 0.05 0.03 0.02 0.01

What is the probability that a randomly selected person would be a Democrat who was not Jewish? a).93 b).50 c).47 d).07

#### Solution Preview

1) The odds of the Dallas Cowboys winning this year's Super Bowl are 3 to 1. Compute the probability of the Cowboys winning.

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The phrase "odds are 3 to 1" means that the opposing team is 3 times as likely to win as the Cowboys. This means that the Cowboys have a 25% chance of winning and the other team has a 75% chance (75% + 25% = 100% and 75% is 3 times as large as 25%).

The answer is b) 0.25.

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2) An appliance dealer calculated the proportion of new dishwashers sold that ...