Question

A simple random sample of 30 items resulted in a sample mean of 50. The population standard deviation is σ = 10.

a. Compute the 95% confidence interval for the population mean. Round your answers to one decimal place.
Enter your answer using parentheses and a comma, in the form (n1,n2). Do not use commas in your numerical answer (i.e. use 1200 instead of 1,200, etc.)

b. Assume that the same sample mean was obtained from a sample of 90 items. Provide a 95% confidence interval for the population mean. Round your answers to two decimal places.

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

Larger sample provides a - Select your answer -larger OR smaller margin of error.

Answer 1

a)

from above 95% CI =46.4 ; 53.6

b)

as above:

for sample size n=90 ;95% CI =47.93 ;52.07

c)

Larger sample provides a  smaller margin of error.