Question

A population has a mean of 800 and a standard deviation of 200. Suppose a sample of size 400 is selected and x is used to estimate μ. (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?

A simple random sample of 90 items resulted in a sample mean of 70. The population standard deviation is

σ = 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 of 180 items. Provide a 95% confidence interval for the population mean. (Round your answers to two decimal places.)

to

(c)

What is the effect of a larger sample size on the interval estimate?

A larger sample size provides a smaller margin of error.A larger sample size provides a larger margin of error.    A larger sample size does not change the margin of error.

Answer 1