In: Statistics and Probability
Parents of potential WKU students often express an interest in making sure their child can graduate in 4 years. To do so, students must complete an average of 15 credit hours per semester. A random sample of 250 students at WKU finds that these students take a mean of 14.7 credit hours per semester with a standard deviation of 1.9 credit hours. Assume the sample standard deviation is equal to the population standard deviation. Estimate the mean credit hours taken by a student each semester using a 95% confidence interval. Round to the nearest thousandth. (Note that the options give the answer in the format of sample mean +/- the margin of error).
14.7 ± .171 |
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14.7 ± .236 |
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14.7 ± .015 |
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14.7 ± .011 |
Parents of potential WKU students often express an interest in making sure their child can graduate in 4 years. To do so, students must complete an average of 15 credit hours per semester. A random sample of 250 students at WKU finds that these students take a mean of 14.7 credit hours per semester with a standard deviation of 1.9 credit hours. Assume the sample standard deviation is equal to the population standard deviation.
Now, we estimate the mean credit hours taken by a student each semester using a 95% confidence interval.
Since we assume that sample standard deviation as population standard deviation so we use Z-critical value to estimate the 95% CI.
Given that,
Sample Mean = 14.7 and Population Standard Deviation = 1.9 and Sample Size = 250
Level of significance:-
Critical Value:-
[ Value are getting from Z-table ]
Margin of Error:-
Now we put the value of , , and we get,
[ Round to the nearest thousandth ]
95% Confidence Interval For Population Mean:-
Now we put the value of MOE and and we get,
i.e. 95% confidence interval for population mean is given by,
Answer:- Correct answer is " 2nd Option "