Question

A simple random sample of 10 observations was taken from a large normal population. the sample mean and the population standard deviation were determined to be 80 and 12, respectively. a 99% population mean confidence interval is approximately ____.

Answer 1

What we are looking for is the confidence interval.

Given:

Sample it is denoted by n = 10 

Mean = 80

Standard deviation = 12

Confidence Interval = 99%


Now compute for the margin of error, the formula is Za/2 * σ/√(n)


A 99% level of confidence has a critical value of zα/2 = 2.58.


The standard error is σ/√(n) = 3.162


Multiply 2.58 by 3.162 = 9.8 is the margin of error.


The formula for confidence interval is x̅ ± Za/2 * σ/√(n)

= 80 ± 9.8

= 70.2 < x< 89.8