Introduction to Normal Distributions

Pre-Test

The annual salaries of all employees at a financial company are normally distributed with a mean of [tex]$\$[/tex]34,000[tex]$ and a standard deviation of $[/tex]\[tex]$4,000$[/tex]. What is the [tex]$z$[/tex]-score of a company employee who makes an annual salary of [tex]$\$[/tex]54,000[tex]$?

A. $[/tex]-5[tex]$

B. $[/tex]-3$

C. 4

D. 5



Answer :

To find the z-score of a company employee who makes an annual salary of [tex]$54,000, we need to use the formula for calculating the z-score in a normal distribution: \[ z = \frac{X - \mu}{\sigma} \] Where: - \( X \) is the value of the data point (the employee's salary, in this case, $[/tex]54,000).
- [tex]\( \mu \)[/tex] is the mean of the data (the average salary, which is [tex]$34,000 in this case). - \( \sigma \) is the standard deviation of the data (the standard deviation of the salaries, given as $[/tex]4,000).

Let's plug these values into the formula:

[tex]\[ z = \frac{54000 - 34000}{4000} \][/tex]

First, compute the difference in the numerator:

[tex]\[ 54000 - 34000 = 20000 \][/tex]

Next, divide the result by the standard deviation:

[tex]\[ z = \frac{20000}{4000} \][/tex]

[tex]\[ z = 5 \][/tex]

Therefore, the z-score of a company employee who makes an annual salary of $54,000 is [tex]\( 5 \)[/tex]. This means that the employee's salary is 5 standard deviations above the mean salary.

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