Question 472941: 1. A company that produces flashlight batteries wishes to know what percentage of its batteries will last longer than 30 hours. It selects and tests a random sample of 1,100 batteries. Of these batteries, 1,065 last 30 hours or more.
Find the 95% confidence interval for the percentage of batteries that last 30 hours or more. Please round the answers to the nearest tenth.
a. 95.5% to 97.9%
b. 95.8% to 98.2%
c. 95.5% to 98.2%
d. 95.8% to 97.9%
e. 95.9% to 97.7%
2. Find the standard error for a sample proportion of 50%, given the following sample size. 50
a. s 0.070
b. s 0.062
c. s 0.071
d. s 0.083
e. s 0.056
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 1. A company that produces flashlight batteries wishes to know what percentage of its batteries will last longer than 30 hours. It selects and tests a random sample of 1,100 batteries. Of these batteries, 1,065 last 30 hours or more.
Find the 95% confidence interval for the percentage of batteries that last 30 hours or more. Please round the answers to the nearest tenth.
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sample proportion: 1065/1100 = 0.968
ME = 1.96*sqrt[0.968*0.032/1100] = 0.010
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95% CI: 0.968-0.010 < p < 0.968+0.010
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95% CI: 0.958 < p < 0.978
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a. 95.5% to 97.9%
b. 95.8% to 98.2%
c. 95.5% to 98.2%
d. 95.8% to 97.9%
e. 95.9% to 97.7%
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2. Find the standard error for a sample proportion of 50%, given the following sample size. 50
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std of sample proportions: sqrt[0.5*0.5/50] = 0.0707..
Cheers,
Stan H.
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a. s 0.070
b. s 0.062
c. s 0.071
d. s 0.083
e. s 0.056
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