To solve this problem, we will follow these steps:

Given:

• We have a dataset of pulse rates for nine students.
• We need to calculate the $z$-scores for each student's pulse rate.
• Then, we will compute the mean and standard deviation of the resulting $z$-scores.

Formula for the $z$-score:

$z = \frac{X - \mu}{\sigma}$

Where:

• $X$ is the individual student's pulse rate.
• $\mu$ is the mean of the pulse rates.
• $\sigma$ is the standard deviation of the pulse rates.

Steps:

1. Calculate the mean $\mu$ of the population (the nine pulse rates).
2. Calculate the standard deviation $\sigma$ of the population.
3. Calculate the $z$-score for each pulse rate using the formula above.
4. Calculate the mean and standard deviation of the $z$-scores.

Please provide the pulse rates for the nine students so I can continue with the calculations.