9. Correct. The answer is true.
First of all, you have to calculate the expected value of the sample. It is simply the average of the prices. Let P the copper price. The expected value μ is:
Second, you have to calculate the standard deviation. The formula of the variance of the sample prices is:
where “n” is the number of observations. Applying this formula to the information in the table:
The standard deviation is: (σ2)0.5 = 17.49.
The standardized prices can be obtained by applying the following formula to each sample price in the table:
The result is: