155ST3C7­10 Problems from Sample Test 3
MAT 155 Statistical Analysis
December 07, 2010
1. Construct a 95% confidence interval for the population proportion p with the sample data n = 53 and
x = 15.
﴾a﴿ ﴾ 0.162, 0.404﴿ ﴾b﴿ ﴾ 0.18, 0.386﴿ ﴾c﴿ ﴾ 0.161, 0.405﴿ ﴾d﴿ ﴾ 0.181, 0.385﴿
Dr. Claude Moore
Cape Fear Community College
Review for Test 3
Chapters 7, 8, 9, & 10
2. Find the critical value t for a confidence level of 99 and a sample size of 17.
﴾d﴿ 2.898
﴾c﴿ 2.921 ﴾b﴿ 2.583 ﴾a﴿ 2.567 Problems from Sample Test 3
3. Identify the null hypothesis H0 and the alternative hypothesis H1. Use μ for a claim about a mean, p for a
claim about a proportion, and for a claim about standard deviation. A researcher claims that the amounts
of acetaminophen in a certain brand of cold tablets have a standard deviation different from 3.3 mg.
﴾b﴿ H0: σ ≠ 3.3 mg H : σ = 3.3 mg
﴾a﴿ H0: σ ≥ 3.3 mg H : σ < 3.3 mg ﴾d﴿ H0: σ = 3.3 mg H : σ ≠ 3.3 mg
﴾c﴿ H0: σ ≤ 3.3 mg H : σ > 3.3 mg 4. Formulate the indicated conclusion by using the flow chart from the formula card. Be sure to address the
original claim. A psychologist claims that more than 37 percent of the population suffers from professional
problems due to extreme shyness. Assume that a hypothesis test of the claim has been conducted and that the conclusion is fail to reject the null hypothesis, state the conclusion in non­technical terms.
﴾a﴿ There is not sufficient evidence to support the claim that the true proportion is less than 37 percent.
﴾b﴿ There is sufficient evidence to support the claim that the true proportion is greater than 37 percent.
﴾c﴿ There is sufficient evidence to support the claim that the true proportion is less than 37 percent.
﴾d﴿ There is not sufficient evidence to support the claim that the true proportion is greater than 37 percent.
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155ST3C7­10 Problems from Sample Test 3
5. Compute the value of an appropriate test statistic for the given hypothesis test. You wish to test the claim that μ < 25.0 with a significance level of α = 0.05. In a sample of n = 52, the sample mean is 27.1, and the population standard deviation is 3.3.
﴾a﴿ z = ­4.59 ﴾b﴿ z = 33.09 ﴾c﴿ z = 4.59 December 07, 2010
7. Should the statistician use a t distribution, a normal distribution, or neither to test the null hypothesis? In a
study of monthly incomes, x = 4070, σ = 1980, and n = 7. The data has a slight skew to the right.
The null hypothesis is: Ho: μ ≤ 4400
﴾c﴿ Neither
﴾b﴿ t distribution ﴾a﴿ Normal distribution ﴾d﴿ z = 0.64
6. Find the critical t­value or values for the given hypothesis, sample size, and significance level. α = 0.01;
n = 12; H0: μ = 81.1
﴾a﴿ ±3.106 ﴾b﴿ 2.718 ﴾c﴿ ±2.718 ﴾d﴿ ±3.055
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155ST3C7­10 Problems from Sample Test 3
December 07, 2010
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155ST3C7­10 Problems from Sample Test 3
December 07, 2010
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