# week 3 practice

1. Find the area under the standard normal curve. Round to four decimal places.

 Question Answer a. between z = 0 and z = 1.95 .9744 b. between z = 0 and z = −2.05 c. between z = 1.15 and z = 2.37 d. from z = −1.53 to z = −2.88

2. The F distribution is:

 Question Answer a. Discrete or continuous? b. Symmetrical, skewed to the right, or skewed to the left? c. Like the normal or Z distribution, the F distribution can have negative values. True or False?

3. Find the critical value of F for the following. Round to two decimal places.

 Question Answer a. df = (3, 3) and area in the right tail = .05 b. df = (3, 10) and area in the right tail = .05 c. df = (3, 30) and area in the right tail = .05

4. The following ANOVA table is based on information obtained for three samples selected from three independent populations that are normally distributed with equal variances. You have all of the information you need (below) to fill in the six missing values (Roman numerals). The intermediate numbers must correctly result in F = 2.16. Round to four decimal places and mark with bold. Use Tables 12.3 and 12.4 (p. 498) as a guide.

 Source of Variation Degrees of Freedom Sum of Squares Mean Square Value of the Test Statistic Between 2 II 19.2813 Within 89.3677 III F = ___V__ = 2.16               VI Total 12 IV

5. Using F = 2.16 and α = .01, what is your conclusion regarding

Ho: the means of the three populations are all equal

Ha: the means of the three populations are not all equal?

Use Table VII critical values of F for .01 (p. B24). (One choice is TRUE; the other three are FALSE.)

 Question Answer a. Reject H0. Conclude that the means of the three populations are equal. b. Reject H0. Conclude that the means of the three populations are not equal. c. Do not reject H0. Conclude that the means of the three populations are equal. d. Do not reject H0. Conclude that the means are of the three populations are not equal.