Answer:

And we can solve this using the following z score formula:

And if we use this formula we got:

So we can find this probability equivalently like this:

Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the heights of a population, and for this case we know the distribution for X is given by:
Where
and
We select n =100. Since the distribution for X is normal then we know that the distribution for the sample mean
is given by:
We want this probability:

And we can solve this using the following z score formula:

And if we use this formula we got:

So we can find this probability equivalently like this:

Answer; c^2 = a^2 + b^2
c = 17 inches
a = 8 inches
b^2 = c^2 – a^2
b^2 = 17^2 – 8^2
b^2 = 289 – 64
b^2 = 225
b = square root of 225
b = 15 inches ≈ c.
Means the number you can use
remember we can't divide by zero
domain is x^2-9
set to zero to find values we can't use
x^2-9=0
x^2=9
x=+/-3
domain=all real numbers except -3 and 3
See the attached picture for the answers: