Answer:
The standard deviation of the age distribution is 6.2899 years.
Step-by-step explanation:
The formula to compute the standard deviation is:
The data provided is:
X = {19, 19, 21, 25, 25, 28, 29, 30, 31, 32, 40}
Compute the mean of the data as follows:
Compute the standard deviation as follows:
Thus, the standard deviation of the age distribution is 6.2899 years.
Answer:
1,082
Step-by-step explanation:
The sample size n in Simple Random Sampling is given by
where
z = 1.645 is the critical value for a 90% confidence level (*)
s = 2 is the estimated population standard deviation
e = 0.1 mm points is the margin of error
so
rounded up to the nearest integer.
So the manufacturer should test 1,083 parts.
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(*)This is a point z such that the area under the Normal curve N(0,1) outside the interval [-z, z] equals 10% = 0.1
It can be obtained in Excel with
NORMINV(1-0.05,0,1)
and in OpenOffice Calc with
NORMINV(1-0.05;0;1)