If the sample mean is 51,sample size is 21 , sample standard deviation is 15 and confidence level is 95% then the lower bound is 45.35 and upper bound is 56.65.
Given sample mean of 51, sample size of 21, sample standard deviation be 15 and confidence level be 95%.
We are required to find the upper bound and lower bound.
We have to use t test as the sample size is less than 30.
Margin of error is the difference between calculated figures and real figures.
Margin of error= standard deviation* critical value of t
Critical value of t at 0.05 significance level with degree of freedom 20 [21-1] is 1.7247.
Margin of error=1.7247*15/4.5826
(4.5826 is the square root of 21)
=5.6454
Upper bound=51+5.6454
=56.6454
Lower bound=51-5.6454
=45.3546
After rounding off they will be 56.65 and 45.35.
Hence if the sample mean is 51,sample size is 21 , sample standard deviation is 15 and confidence level is 95% then the lower bound is 45.35 and upper bound is 56.65.
Learn more about margin of error at https://brainly.com/question/10218601
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