A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5.

Question

a. What is the standard error of the mean (to 2 decimals)?
b. At 95% confidence, what is the margin of error (to 2 decimals)?

Answer 1

Part a)
SE of mean = sd/√n = 5/√40

Part b)
ME = 1.96 * 5/√40

I'll let you finish the calculations.

Answer 2

.80

Answer 3

A) 0.79
B) 1.55