You may need to use the appropriate appendix table or technologyto answer this question.
A simple random sample of 60 items resulted in a sample mean of90. The population standard deviation is
? = 15.
(a)
Compute the 95% confidence interval for the population mean.(Round your answers to two decimal places.)
( )to( )
(b)
Assume that the same sample mean was obtained from a sample of120 items. Provide a 95% confidence interval for the populationmean. (Round your answers to two decimal places.)
( )to( )
(c)
What is the effect of a larger sample size on the intervalestimate?
A. A larger sample size does not change the margin of error.
B. A larger sample size provides a smaller margin oferror.
C. A larger sample size provides a larger margin of error.
