For the data of Exercise 1.4 on page 13, compute both the mean and variance in “flexibility” for both company A and company B.
For the company A:
We know, based on our answer in Exercise 1.4, that the sample mean for samples in Company A is .
To compute for the sample variance, we shall use the formula
The formula states that we need to get the sum of , so we can use a table to solve for every sample.
Note: You can refer to the solution of Exercise 1.7 on how to use a table to solve for the variance.
The variance is
The standard deviation is just the square root of the variance. That is
For Company B:
Using the same method employed for Company A, we can show that the variance and standard deviation for the samples in Company B are