A researcher estimated an unknown population standard deviation ...

[K@]

A researcher estimated an unknown population standard deviation to be 150 . Using a sample of size n = 135, the sample standard deviation was found to be 100 . The researcher now wishes to establish a 95 confidence interval for the population mean. Which of the following is the correct standard error of the mean to use in calculating the desired confidence interval?
 a. Can't be determined from the information given.
  b. 1.05
  c. 12.91
  d. 0.86
  e. 8.61

Question 2

In the above problem, if the desired precision is +25 and the desired confidence interval is 95, what is the necessary sample size?
 a. 240
  b. 540
  c. 92
  d. 64
  e. None of the above.

[Anonymous]

Answer to Question 1

E

Answer to Question 2

D

[K@]

Great answer, keep it coming

[amcvicar]

Thanks for the timely response, appreciate it