Question

WHERE is the for a 95 % confidence interval where the population variance is known to be 100 the sample average is 50 and the number of people samples are 64 what is the value of z what is the standard deviation what is n what is one what is the confidence interval

Answer 1

95% Confidence Interval for Known Population Standard Deviation

Given: = sample mean = 50, (Variance)= 100

Therefore = population standard deviation = sqrt(Variance) = sqrt(100) = 10,

n = sample size = 64

= 100 - 95 = 5% = 0.05 and Zcritical (2 tailed) = 1.96 (We can use standard normal tables or use the Excel formula NORMSINV)

The Confidence Interval is given by ME, where

The Lower Limit = 50 - 2.45 = 47.55

The Upper Limit = 50 + 2.45 = 52.45

The 95% Confidence Interval is (47.55 , 52.45)