A population has a mean of 128 and a standard deviation of 32.Suppose a sample of size 64 is selected and x is used to estimate?. (Round your answers to four decimal places.)
(a) What is the probability that the sample mean will be within±5 of the population mean?
(b) What is the probability that the sample mean will be within±10 of the population mean?
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 of70. The population standard deviation is
? = 5.
(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 larger sample size provides a larger margin of error.A largersample size provides a smaller margin oferror. A larger sample size does not changethe margin of error.
