A small diner gets its eggs from two different suppliers. Uniformity of the weight of the eggs is an important quality parameter on which the suppliers are judged. A sample of 35 eggs from supplier A had a standard deviation in weight of 1.2 gm, while a sample of 45 eggs from supplier B had a standard deviation of .85gm in weight. USING EXCEL: a. Construct a 99% confidence interval for the standard deviation of the weight of eggs provided by supplier A b. At a 2% significance, conduct the appropriate hypothesis test to determine if there is any difference in the standard deviation of weight of eggs provided by the two suppliers.
A small diner gets its eggs from two different suppliers. Uniformity of the weight of the eggs is an important quality parameter on which the suppliers are judged. A sample of 35 eggs from supplier A had a standard deviation in weight of 1.2 gm, while a sample of 45 eggs from supplier B had a standard deviation of .85gm in weight.
USING EXCEL:
a. Construct a 99% confidence interval for the standard deviation of the weight of eggs provided by supplier A
b. At a 2% significance, conduct the appropriate hypothesis test to determine if there is any difference in the standard deviation of weight of eggs provided by the two suppliers.
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Given
For supplier A
sample size
standard deviation
For supplier B
sample size
standard deviation
a)
The confidence interval for standard deviation is calculated using the below shown formula
For supplier A
s
n
degree of freedom
As we need 99% confidence interval
Using Excel function CHISQ.INV(Probability, degree of freedom) we find the critical values
Entering the following function in excel we get
=CHISQ.INV(0.995,34) = 58.96393
=CHISQ>INV(0.005,34) = 16.50127
Using these values we get the 99% confidence interval as shown below
The 99% confidence interval for standard deviation of weight of eggs provided by supplier A is (0.911, 1.723)
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