**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:
(σ^{2})^{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: