To calculate Isaac's z-score, you can use the formula for the z-score:
\[ z = \frac{(X - \mu)}{\sigma} \]
where:
- \(X\) is the value you are examining (Isaac's candies received, which is 40),
- \(\mu\) is the mean (average number of candies, which is 50),
- \(\sigma\) is the standard deviation (which is 12).
Plugging in the values:
\[ z = \frac{(40 - 50)}{12} = \frac{-10}{12} \approx -0.83 \]
Thus, Isaac's z-score, rounded to the nearest hundredth, is:
\[ z \approx -0.83 \]
For Trina, who received 47 pieces of candy, we can calculate her z-score in the same way:
\[ z = \frac{(X - \mu)}{\sigma} \]
where \(X = 47\).
Now, substituting the values:
\[ z = \frac{(47 - 50)}{12} = \frac{-3}{12} = -0.25 \]
Thus, Trina's z-score, rounded to the nearest hundredth, is:
\[ z \approx -0.25 \]