A study of 80 white mice showed that their average weight wa

A study of 80 white mice showed that their average weight was 4.7 ounces. The standard deviation of the population is 0.8 ounces. Which of the following is the 80% confidence interval for the mean weight per white mouse?

Solution

Confidence Interval
CI = x ± Z a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
Za/2 = Z-table value
CI = Confidence Interval
Mean(x)=4.7
Standard deviation( sd )=0.8
Sample Size(n)=80
Confidence Interval = [ 4.7 ± Z a/2 ( 0.8/ Sqrt ( 80) ) ]
= [ 4.7 - 1.28 * (0.089) , 4.7 + 1.28 * (0.089) ]
= [ 4.586,4.814 ]