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