
A First Course in Probability (10th Edition)
10th Edition
ISBN: 9780134753119
Author: Sheldon Ross
Publisher: PEARSON
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Transcribed Image Text:Problem 9
According to the federal government, 24% of workers covered by their company's health care plan were not
required to contribute to the premium (Statistical Abstract of the UnitedStates: 2006). A recent study found that
81 out of 400 workers sampled were not required to contribute to their company's health care plan. Has the
percent of workers not required to contribute to their company's health plan decreased? Test at the 99%
confidence level.

Transcribed Image Text:For these problems you should complete the 8 steps of the hypothesis testing process.
State the null and alternative hypotheses.
Specify alpha (a) based on the confidence level indicated.
Use alpha to develop the critical value that delineates the rejection region. Remember to use a/2
for two-tailed tests. Draw the curve and indicate the rejection region.
Use information from the problem to compute the test statistic
Calculate P-value based on test statistic.
1.
2.
3.
4.
5.
a) If population standard deviation or proportion use Z or normal distribution table
One tail: 0.5 – area in non cum table.
Two tailed: PV = 2* (0.5- area in non cum table)
b) If sample standard deviation use t table with df = n-1.
PV will be a range..e.g. 0.025 to 0.05.
Compare the test statistic to the critical value. Compare the P-value to alpha.
Based on your comparisons identify your decision (i.e. reject null hypothesis Ho or fail to reject
null hypothesis Ho). Reject the null hypothesis if the test statistic is in the rejection region.
Reject the null hypothesis if the P-value is smaller than alpha. The outcome of the p-value and
critical value approach will always lead to the same decision.
Indicate the conclusion for the scenario
6.
7.
8.
IF Reject Ho: at % (confidence level indicated) can conclude Ha
IF Fail to Reject Ho: at % (confidence level indicated) can NOT conclude Ha
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