AP Statistics / Mr. Hansen
Take-Home Quizzes Distributed 12/15/2000

Name: _________________________

Quiz 7.1A

For problems 1-4, the probabilities that a customer selects 1, 2, 3, 4, or 5 items at a convenience store are 0.32, 0.12, 0.23, 0.18, and 0.15, respectively.

1.

Construct a probability distribution (table) for the data, and draw a probability distribution histogram.

2.

Find P(X > 3.5).

3.

Find P(1.0 < X < 3.0).

4.

Find P(X < 5).

For problems 5-9, a certain probability density function is made up of two straight line segments. The first segment begins at the origin and goes to the point (1, 1). The second segment goes from (1, 1) to the point (x, 1).

5.

Sketch the distribution function, and determine what x has to be in order to make a legitimate density curve.

6.

Find P(0 < X £ 0.5).

7.

Find P(X = 1).

8.

Find P(0 < X < 1.25).

9.

Circle the correct option: X is an example of a (discrete) (continuous) random variable.

Quiz 7.2B

For problems 1-6, a distribution of grades in an introductory statistics class (where A=4, B=3, etc.) is as follows:

0

1

2

3

4

P(X)

.10

.15

.30

.30

.15

1.

A graduate student needs at least a B to get credit for the course. What are her chances of getting at least a B?

2.

Find P(1 £ X < 3).

3.

Find the average (i.e., mean) grade in this class.

4.

Find the standard deviation for the class grades.

5.

Find the lowest grade X₀ such that P(X ³ X₀) < 0.5.

6.

Circle the correct answer: X is an example of a (discrete) (continuous) random variable.

7.

A lottery offers one $1,000 prize, one $500 prize, and five $100 prizes. One thousand tickets are sold at $3 each. Find the expectation (expected value) if a person buys one ticket.