MATH 110 Exam 8 Statistics Questions and
Answers- Portage Learning
1. . Independent random samples were selected from population 1 and population 2. The
n n n n n n n n n n n n
following information was obtained from these samples:
n n n n n n n
a) Find the 95% confidence interval for estimating the difference in the population means(µ -
n n n n n n n n n n n n n n 1nn n
µ ).
n 2
Solution. When we look back at table 6.1, we see that 95% confidence corresponds to z=1.96.
n n n n n n n n n n n n n n n
a) Notice that the sample sizes are each greater than 30, so we may use eqn. 8.1:
n n n n n n n n n n n n n n n
b) Notice that the 95% confidence interval covers both positive and negative values. Therefore,we
n n n n n n n n n n n n n
cannot be 95% confident that there is a difference in the two population means.
n n n n n n n n n n n n n n
2. 2. A company would like to determine if there is a difference in the number of days that
n n n n n n n n n n n n n n n n n
employees are absent from the East Side Plant compared to the West Side Plant. So, the
n n n n n n n n n n n n n n n n
company takes a sample of 54 employees from the East Side Plant and finds that these
n n n n n n n n n n n n n n n n
people missed an average of 5.3 days last year with a standard deviation of 1.3 days. A
n n n n n n n n n n n n n n n n n
sample of 41 employees from the West Side plant revealed that these people were absentan
n n n n n n n n n n n n n n n n
average of 6.8 days last year with a standard deviation of 1.8 days.
n n n n n n n n n n n n n
a) Find the 96% confidence interval for estimating the difference in the population means(µ -
n n n n n n n n n n n n n n 1nn n
µ ).
n 2
Solution. When we look back at table 6.1, we see that 96% confidence corresponds to z=2.05.If we
n n n n n n n n n n n n n n n n n
say that the East Side Plant corresponds to population 1 and the West Side Plant corresponds to
n n n n n n n n n n n n n n n n n
population 2, then:
n n n
n =54, n =41, s =1.3, s =1.8, xぁ= 5.3, x あ= 6.8,
1 n 2 n 1 n 2 n n n n n n n n
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n n n n n n n n n n n n n
https://www.coursehero.com/file/81393958/MATH-110-Module-8-ANSWERSdocx/
, a) We will use eqn. 8.1:
n n n n
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n n n n n n n n n n n n n
https://www.coursehero.com/file/81393958/MATH-110-Module-8-ANSWERSdocx/
Answers- Portage Learning
1. . Independent random samples were selected from population 1 and population 2. The
n n n n n n n n n n n n
following information was obtained from these samples:
n n n n n n n
a) Find the 95% confidence interval for estimating the difference in the population means(µ -
n n n n n n n n n n n n n n 1nn n
µ ).
n 2
Solution. When we look back at table 6.1, we see that 95% confidence corresponds to z=1.96.
n n n n n n n n n n n n n n n
a) Notice that the sample sizes are each greater than 30, so we may use eqn. 8.1:
n n n n n n n n n n n n n n n
b) Notice that the 95% confidence interval covers both positive and negative values. Therefore,we
n n n n n n n n n n n n n
cannot be 95% confident that there is a difference in the two population means.
n n n n n n n n n n n n n n
2. 2. A company would like to determine if there is a difference in the number of days that
n n n n n n n n n n n n n n n n n
employees are absent from the East Side Plant compared to the West Side Plant. So, the
n n n n n n n n n n n n n n n n
company takes a sample of 54 employees from the East Side Plant and finds that these
n n n n n n n n n n n n n n n n
people missed an average of 5.3 days last year with a standard deviation of 1.3 days. A
n n n n n n n n n n n n n n n n n
sample of 41 employees from the West Side plant revealed that these people were absentan
n n n n n n n n n n n n n n n n
average of 6.8 days last year with a standard deviation of 1.8 days.
n n n n n n n n n n n n n
a) Find the 96% confidence interval for estimating the difference in the population means(µ -
n n n n n n n n n n n n n n 1nn n
µ ).
n 2
Solution. When we look back at table 6.1, we see that 96% confidence corresponds to z=2.05.If we
n n n n n n n n n n n n n n n n n
say that the East Side Plant corresponds to population 1 and the West Side Plant corresponds to
n n n n n n n n n n n n n n n n n
population 2, then:
n n n
n =54, n =41, s =1.3, s =1.8, xぁ= 5.3, x あ= 6.8,
1 n 2 n 1 n 2 n n n n n n n n
This study source was downloaded by 100000848594376 from CourseHero.com on 01-16-2023 21:26:16 GMT -06:00
n n n n n n n n n n n n n
https://www.coursehero.com/file/81393958/MATH-110-Module-8-ANSWERSdocx/
, a) We will use eqn. 8.1:
n n n n
This study source was downloaded by 100000848594376 from CourseHero.com on 01-16-2023 21:26:16 GMT -06:00
n n n n n n n n n n n n n
https://www.coursehero.com/file/81393958/MATH-110-Module-8-ANSWERSdocx/
