Fortynine items are randomly selected from a population of 5

Forty-nine items are randomly selected from a population of 500 items. The sample mean is 40 and the sample standard deviation 9.

Develop a 99% confidence interval for the population mean. (Round your answers to 3 decimal places.)

Solution

Answer to the question)

Sample size n = 49

Mean x bar = 40

standard deivation s = 9

Confidence level c = 99% , for it the Z value is 2.575

.

The formula of confidence interval is:

x bar - z * s / sqrt(n) , xbar + z * s / sqrt(n)

.

On plugging the values we get

40 - 2.575 * 9 /sqrt(49) , 40 + 2.575 * 9 / sqrt(49)

36.6893 , 43.3107