Normal Distribution and Obj

Chapter 13: Chi-Square Applications

SHORT ANSWER

1. When samples of size n are drawn from a normal population, the chi-square distribution is the sampling distribution of = ____________________, where s2 and are the sample and population variances, respectively.

ANS:

PTS: 1 OBJ: Section 13.2

2. Find the chi-square value for each of the right-tail areas below, given that the degrees of freedom are 7:

A) 0.95 ____________________

B) 0.01 ____________________

C) 0.025 ____________________

D) 0.05 ____________________

ANS:
2.167; 18.475; 16.013; 14.067

PTS: 1 OBJ: Section 13.2

3. Find the chi-square value for each of the four degrees of freedom below, given that the area to the left of a chi-square value is 0.05.

A) 2 ____________________

B) 6 ____________________

C) 10 ____________________

D) 26 ____________________

ANS:
0.103; 1.635; 3.940; 15.379

PTS: 1 OBJ: Section 13.2

NARRBEGIN: Department store
A large department store records the number of returns per day in women's dresses for reasons such as wrong size; husband didn't like it, color, etc. The manager of the women's dresses department recalls from her statistics class in college that the Poisson distribution might describe such events. A random sample of 150 days is taken. The number of returns per day in the sample as well as the observed frequencies are shown below:

NARREND

4. She tests the hypothesis that returns per day are Poisson distributed with a population mean equal to 1.90. Her significance level is 0.05. State the null and alternative hypotheses.

H0: _______________________________________________________________

H1: _______________________________________________________________

ANS:
H0: The sample was drawn from a population that is Poisson distributed with a mean equal to 1.90.;
H1: The sample was not drawn from such population.

PTS: 1 OBJ: Section 13.3

5. She tests the hypothesis that returns per day are Poisson distributed with a population mean equal