Page 445 - Six Sigma Demystified

f i n a l e x a m 425

66. For a sample of 20 units with an average of 121 and a standard deviation of 15, a
two-sided hypothesis that the standard deviation equals 21 (assuming normality)
yields a result of
A. reject the null hypothesis that the standard deviation equals 21 because the p
value is less than 0.05.
b. reject the null hypothesis that standard deviation equals 21 because the p value is
greater than 0.05.
c. assert that the standard deviation equals 21 because the p value is greater than
0.05.
d. The standard deviation may or may not equal 21; we cannot reject the
hypothesis that the standard deviation equals 21 because the p value is greater
than 0.05.

67. For a sample of 20 units with an average of 121 and a standard deviation of 15,
for an alternative one-sided hypothesis that the standard deviation is less than 21
(assuming normality), we should
A. reject the null hypothesis that the standard deviation is greater than or equal to
21 because the p value is less than 0.05.
b. reject the null hypothesis that standard deviation is greater than or equal to 21
because the p value is greater than 0.05.
c. assert that the standard deviation is greater than or equal to 21 because the p
value is greater than 0.05.
d. The standard deviation may or may not be greater than or equal to 21; we
cannot reject the hypothesis that the standard deviation is greater than or equal
to 21 because the p value is greater than 0.05.

68. In a two-sided hypothesis test to compare the equality of two sample variances
taken from independent samples, if one sample has a standard deviation of
15 from a sample size of 20, and the other sample has a standard deviation
of 21 estimated from a sample of 20, then the test statistic (assuming
normality) is
A. 0.92.
b. 1.96.
c. 0.98.
d. 0.71.

69. In a two-sided hypothesis test to compare the equality of two sample variances
taken from independent samples, if one sample has a standard deviation of 15
from a sample size of 20, and the other sample has a standard deviation of 21
estimated from a sample size of 20, then which of the following conclusions
(assuming normality) should be made?
A. Reject the null hypothesis that the variances are equal because the p value is less
than 0.05.
b. Reject the null hypothesis that the variances are equal because the p value is
greater than 0.05.
c. Assert that the variances are not equal because the p value is greater than 0.05.
d. The variances may or may not be equal; we cannot reject the hypothesis that the
variances are equal because the p value is greater than 0.05.