A shipment of 1000 small lab mice arrives at the animal care

A shipment of 1000 small lab mice arrives at the animal care facility with a nominal weight of 10 g per mouse. A sample of 20 mice is selected and weighed. The average weight of the sample is 10.2 g. From past shipments, it is known that the standard deviation of weight among mice is 2 g. Find a 95% confidence interval for the mean weight of all the mice in the shipment. 10 ± 0.88 10.2 ± 0.88 10 ± 0.44 10 ± 0.88

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)=10.2
Standard deviation( sd )=2
Sample Size(n)=20
Confidence Interval = [ 10.2 ± Z a/2 ( 2/ Sqrt ( 20) ) ]
= [ 10.2 ± 1.96 * (0.447)]
= [ 10.2 ± 0.88 ]

[ANSWER] 10.2 ± 0.88