Section 9.1

Question #4

Since an instant replay system for tennis was introduced at a major tournament, men challenged 1403 referee calls, with the result that 431 of the calls were overturned. Women challenged

778 referee calls, and 229 of the calls were overturned. Use a

0.01 significance level to test the claim that men and women have equal success in challenging calls. Complete parts (a) through (c) below.

Identify the test statistic.

z=________

(Round to two decimal places as needed.)Identify the P-value.

P-value= ________

(Round to three decimal places as needed.)

b. Test the claim by constructing an appropriate confidence interval.

The 99% confidence interval is _________ < p₁p₂ < _________.

(Round to three decimal places as needed.)

Question #5

A study was conducted to determine the proportion of people who dream in black and white instead of color. Among 312 people over the age of 55, 68 dream in black and white, and among 312 people under the age of 25, 10 dream in black and white. Use a 0.05 significance level to test the claim that the proportion of people over 55 who dream in black and white is greater than the proportion for those under 25. Complete parts (a) through (c) below.

Identify the test statistic.

z= _________

(Round to two decimal places as needed.)

Identify the P-value.

P-value= ________

(Round to three decimal places as needed.)

b. Test the claim by constructing an appropriate confidence interval.

The 90% confidence interval is _______< p₁p₂ < ________.

(Round to three decimal places as needed.)

Section 9.2

Question #4

A study was done on proctored and nonproctored tests. The results are shown in the table. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Complete parts (a) and (b) below.

	Proctored	Nonproctored
	1	2
n	32	31
x	77.59	88.58
s	10.85	20.61

The test statistic, t, is _______. (Round to two decimal places as needed.)

The P-value is _______. (Round to three decimal places as needed.)

b. Construct a confidence interval suitable for testing the claim that students taking nonproctored tests get a higher mean score than those taking proctored tests.

___________ < ₁₂ < _________

(Round to two decimal places as needed.)

Question #7

Listed in the data table are IQ scores for a random sample of subjects with medium lead levels in their blood. Also listed are statistics from a study done of IQ scores for a random sample of subjects with high lead levels. Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. Complete parts (a) and (b) below.

View the data table of IQ scores.

IQ scores

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MediumLeadLevel	HighLeadLevel
72	n2 = 11
94
92	x2 = 89.071
85
89	s2 = 9.858
97
83
92
102
111
91

The test statistic is __________. (Round to two decimal places as needed.)

The P-value is _________. (Round to three decimal places as needed.)

b. Construct a confidence interval suitable for testing the claim that the mean IQ scores for subjects with medium lead levels is higher than the mean for subjects with high lead levels.

__________ < 12 < ___________

(Round to two decimal places as needed.)