STA 228 Chapter 5

What is probability?

• A value between zero and one, inclusive, describing the relative possibility (chance or likelihood) an event will occur.

• A process that leads to the occurence of one and onlu one of several possible observations

• A particular result of an experiment.

• A collection of one or more outcomes of an experiment.

How many approaches are used to assign probabilities?

• 2

• 3

• 4

• 5

What are mutually exclusive events?

• The occurence of one event means that none of the other events can occur at the same time.

• At least one of the events must occur when an experiment is conducted.

• The occurence of one event means that one of the other events can occur at the same time.

• Two events must occur when an experiment is conducted.

On February 1, 2003, the Space Shuttle Columbia exploded. This was the second disaster in 123 space missions for NASA. On the basis of this information, what is the probability that a future mission is successfully completed?

• P = 2/123

• P = 1/123

• P = 122/123

• P = 121/123

One card will be randomly selected from a standard 52-card deck. What is the probability the card will be a queen? And which approach to probability did you use to answer this question?

• P = 1/52; Classical approach

• P = 2/52; Empirical approach

• P = 3/52; Empirical approach

• P = 4/52; Classical approach

The Center for Child Care reports on 539 children and the marital status of their parents. There are 333 married, 182 divorced, and 24 widowed. What is the probability a particular child chosen at random will have a parent who is divorced? Which approach did you use?

• (333-182)/539; Empirical approach

• 182/539; Empirical approach

• 333/539 ; Classical approach

• 182/539; Classical approach

What is Joint probability?

• A probability that measures the likelihood two or more events will happen concurrently.

• A value between zero and one, inclusive, descrbing the relative possibility (chance or likelihood) an event will occur.

• The probability of en event happening is the fraction of the time similar events happened in the past

• The occurence of one event means that none of the other events can occur at the same time.

From experience, Teton Tire knows the probability is .95 that a particular XB-70 tire will last 60,000 miles before its become bald or fails. An adjustment is made on any tire that does not last 60,000 miles . You buy four XB-70s. What is the probability all four tires will last at least 60,000 miles?

• P = 0.95

• P= 0.95 * 0.95

• P = 0.95 * 0.95 * 0.95

• P = 0.95 * 0.95 * 0.95 * 0.95

The events A and B are mutually exclusive. Suppose P(A) = .30 and P(B) = 0.20. What is the probability of either A or B occuring?

• P(A or B) = 0.5

• P(A or B) = 0.06

• P(A or B) = 0.3

• P(A or B) = 0.2

The Women's Shopping Network on cable TV offers sweaters and slacks for women. The seaters and slacks are offered in coordinating colors. If sweaters are availablr in five colors and the slacks are available in four colors, how many different outfits can be advertised?

• 5

• 4

• 20

• 9