Answer:

Step-by-step explanation:
The z-score tells us how many standard deviations a value is away from the mean.
The formula is:

where x is the value,
is the mean, and s is the standard deviation.
We want to find the z-score for the score of an 83, the mean is 72, and the standard deviation is 5.

Substitute the values into the formula.

Solve the numerator.

Divide.

The z-score is 2.2, which means the score of 83 is 2.2 standard deviations above the mean.
Yes, it will always be a rational number. I'll expound on this by defining what a rational number is. It is any number that can be expressed as a fraction. Otherwise, it is called an irrational number with a non-terminating decimal expansion. So, although 1/3 has a non-terminating decimal expansion because it is equal to 0.33333333...., it is still a rational number because it can be expressed into a fraction.