Answer:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:

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 variable of interest of a population, and for this case we know the distribution for X is given by:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:

answer is attached below with full explanation
The ratio 12:20 because you need it to be equal to 3:5. 3 times 4 which makes 12 so you need to multiply 5 with 4 too
Answer:
ok
Step-by-step explanation:
Answer
Are of the pool = w² + 5w (in square feet)
Explanation
Since the pool is rectangular in shape,
Area of the pool can be calculated using the formula for the area of a rectangle
Area of rectangle = length x width
Given,
Width of pool (Assume is same as height) = w
Length of pool= w + 5
Area = w * (w + 5)
= w² + 5w (in square feet)
where w is the width of the pool