Pulse rates of women are normally distributed with a mean of 77.5 beats per minute and a standard deviation of 11.6 beats per minute. Answer the following questions.

What are the values of the mean and standard deviation after converting all pulse rates of women to [tex]$z$[/tex] scores using [tex]$z=\frac{(x-\mu)}{\sigma}$[/tex]?

[tex]\mu = \ \square[/tex]

[tex]\sigma = \ \square[/tex]



Answer :

To answer this question, we need to understand the concept of converting a data set to [tex]$z$[/tex] scores. This conversion allows us to standardize the data, which simplifies comparison between different sets of data.

### Conversion to [tex]$z$[/tex] Scores:
The formula to convert a data value [tex]\( x \)[/tex] to a [tex]$z$[/tex] score is given by:
[tex]\[ z = \frac{(x - \mu)}{\sigma} \][/tex]
where:
- [tex]\( x \)[/tex] is the original data value,
- [tex]\( \mu \)[/tex] is the mean of the original data set,
- [tex]\( \sigma \)[/tex] is the standard deviation of the original data set.

### Step-by-Step Solution:

1. Mean Calculation:

When converting an entire data set to [tex]$z$[/tex] scores, each value [tex]$x$[/tex] in our data set is standardized by subtracting the mean [tex]\(\mu\)[/tex] and then dividing by the standard deviation [tex]\(\sigma\)[/tex]. Because we adjust each data point in the same manner, the new mean of our [tex]$z$[/tex] score distribution will always be 0.

[tex]\[ \mu_{z} = 0 \][/tex]

2. Standard Deviation Calculation:

Standardizing does not change the spread of the distribution in a relative sense; it only adjusts the scale. Hence, the standard deviation of a distribution of [tex]$z$[/tex] scores is always 1, as we convert every standard deviation unit of the original distribution into exactly one unit on the [tex]$z$[/tex] score scale.

[tex]\[ \sigma_{z} = 1 \][/tex]

### Conclusion:
When all pulse rates of women are converted to [tex]$z$[/tex] scores:

- The mean of the [tex]$z$[/tex] scores ([tex]\(\mu_{z}\)[/tex]) becomes [tex]\(\boxed{0}\)[/tex].
- The standard deviation of the [tex]$z$[/tex] scores ([tex]\(\sigma_{z}\)[/tex]) becomes [tex]\(\boxed{1}\)[/tex].