Name:______________________________________
Module 2 Homework Assignment
1.) 459 randomly selected light bulbs were tested in a laboratory, 291 lasted
more than 500 hours. Find a point
estimate of the true proportion of all light bulbs that last more than 500
hours.
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2.) Find the critical value for zα/2that corresponds to a degree of
confidence of 98%.
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3.) Find the critical value for tα/2
corresponding to n = 12 and 95%
confidence level.
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4.)
Use the confidence level and sample data to find the margin of error E.
College students’ annual
earnings:
99% confidence, n = 74, 
= $3967, s =
$874
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5.) Construct the confidence interval for question 4 above.
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6.) Write a statement that correctly interprets the confidence interval
found in question 5.
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7.) Find the critical
value
corresponding
to a sample size of 19 and a confidence level of 99%.
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8.) Find the critical value
corresponding
to a sample size of 19 and a confidence level of 99%.
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9.)
The values listed below are the waiting times (in minutes) of customers
at the Bank of Providence, where customers enter any one of three different
lines that have formed at three teller windows.
Construct a 95% confidence interval for the population standard
deviation
and write a statement that correctly
interprets the results.
4.2 5.4 5.8 6.2 6.7 7.7 8.5 9.3 10.0
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10.)You want to estimates for the population of waiting times at a
fast-food restaurant’s drive-up windows, and you want to be 95% confident that
the sample standard deviation is within 20% ofs. Find
the minimum sample size needed. Is this
sample size practical?
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