# 11.15: Chapter Solution (Practice + Homework)


1.

mean = 25 and standard deviation = 7.0711

3.

when the number of degrees of freedom is greater than 90

5.

$$df = 2$$

6.

a test of a single variance

8.

a left-tailed test

10.

$$H_0: \sigma^2 = 0.812$$;

$$H_a: \sigma^2 > 0.812$$.

12.

a test of a single variance

16.

a goodness-of-fit test

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3

20.

2.04

21.

We decline to reject the null hypothesis. There is not enough evidence to suggest that the observed test scores are significantly different from the expected test scores.

23.

$$H_0$$: the distribution of AIDS cases follows the ethnicities of the general population of Santa Clara County.

25.

right-tailed

27.

2016.136

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• 30.

a test of independence

a test of independence

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8

36.

6.6

39.

Smoking level per dayAfrican AmericanNative HawaiianLatinoJapanese AmericansWhiteTotals
1-109,8862,74512,8318,3787,65041,490
11-206,5143,0624,93210,6809,87735,065
21-301,6711,4191,4064,7156,06215,273
31+7597888002,3053,9708,622
Totals18,8308,01419,96926,07827,55910,0450
Table $$\PageIndex{54}$$

41.

Smoking level per dayAfrican AmericanNative HawaiianLatinoJapanese AmericansWhite
1-107777.573310.118248.0210771.2911383.01
11-206573.162797.526970.769103.299620.27
21-302863.021218.493036.203965.054190.23
31+1616.25687.871714.012238.372365.49
Table $$\PageIndex{55}$$

43.

10,301.8

44.

right

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1. 48.

test for homogeneity

test for homogeneity

52.

All values in the table must be greater than or equal to five.

54.

3

57.

a goodness-of-fit test

59.

a test for independence

61.

Answers will vary. Sample answer: Tests of independence and tests for homogeneity both calculate the test statistic the same way $$\sum_{(i j)} \frac{(O-E)^{2}}{E}$$. In addition, all values must be greater than or equal to five.

63.

true

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false

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225

69.

$$H_0: \sigma^2 \leq 150$$

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36

72.

Check student’s solution.

74.

The claim is that the variance is no more than 150 minutes.

76.

a Student's $$t$$- or normal distribution

78.

1. 80.
1. 82.
1. 84.
1. 87.
Marital statusPercentExpected frequency
Never married31.3125.2
Married56.1224.4
Widowed2.510
Divorced/Separated10.140.4
Table $$\PageIndex{56}$$
1. 89.
1. 91.
1. 94.

true

false

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1. 100.
1. 102.
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1. 106.
1. 108.

true

true

112.

1. 114.
1. 116.
1. 118.
1. 120.
1. 122.
1. The test statistic is always positive and if the expected and observed values are not close together, the test statistic is large and the null hypothesis will be rejected.
2. Testing to see if the data fits the distribution “too well” or is too perfect.

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