Chapter 5DiscreteProbability Distributions

Question 1

Define and explain what is meant by a probability Distribution of a discrete random variable. Offer an example(s) where necessary to further illustrate its meaning.

Question 2

The following table contains the probability distribution for the number of traffic accidents daily in a small city:

Number of Accidents Daily (X)

P (X = Xi)

0

0.10

1

0.20

2

0.45

3

0.15

4

0.05

5

0.05

a.Compute the mean number of accidents per day and then explain its meaning.

b.Compute the standard deviation and then interpret its meaning. Show your work as to how you have arrived at your answers.

c.Draw the probability distribution; . What conclusion, if any, can you make?

Question 3.

A student is taking a multiple-choice exam in which each question has four choices.Assume that the student has no prior knowledge of the correct answers to any of the questions. She has decided on a strategy in which she will place four balls (marked A, B, C, D) into a box. She randomly selects one ball for each question and replaces the ball in the box. The marking on the ball will determine her answer to the question. There are five multiple-choice questions on the exam. What is the probability that she will get

a.Five questions correct?

b.At least four questions correct.

c.No questions correct.

d.No more than two questions correct.