Author Question: A standard normal distribution is a normal distribution with a. a mean of 1 and a standard ... (Read 143 times)

vHAUNG6011 · **on:** Jun 24, 2018

A standard normal distribution is a normal distribution with
a. a mean of 1 and a standard deviation of 1.
b. a mean of 0 and a standard deviation of 0.
c. any mean and a standard deviation of 1.
d. a mean of 0 and standard deviation of 1.

Question 2

A machine produces pipes used in airplanes. The average length of the pipe is 16 inches. The acceptable variance for the length is .3 inches. A sample of 25 pipes was taken. The average length in the sample was 15.95 inches with a variance of .4 inches.
a. Construct a 95 confidence interval for the population variance.
b. State the null and alternative hypotheses to test whether or not the population variance equals .3 inches.
c. Compute the test statistic.
d. The null hypothesis is to be tested at the 5 level of significance. State the decision rule for the test using the critical value approach.
e. What do you conclude about the population variance?

Dinolord · **Reply #1 on:** Jun 24, 2018

Answer to Question 1

d

Answer to Question 2

a. .244 to .774
b. H0: 2 = .3
Ha: 2 .3
c. 32
d. Do not reject H0 if 12.401 < chi-square < 39.364
Reject H0 if chi-square 39.364 or if chi-square 12.401
e. Do not reject H0; no evidence to conclude that the population variance is different from .3 inches.