Consider the drying time data for Exercise 1.1 on page 13. Compute the sample variance and sample standard deviation.
We know, based on our answer in Exercise 1.1, that the sample mean 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.
The table above shows that
Therefore, the variance is
The standard deviation is just the square root of the variance. That is