Let

be the mean of

. Then

For a random variable

following the standard normal distribution, we have

Transform the random variable to get this critical value in terms of

:
For a standard normal distribution, the expression that is always equal to 1 is P(z≤-a)+P(-a≤z≤a)+P(Z≥a). This expression represents all of the possible values in a curve, or in other words, the total area of a curve. According to standard normal distribution, the total area of a curve is always equal to 1.
P=2 (l+w)
we know P=284
we also know that l= w+50
so replace l in the equation with w+50
284=2 (w+50+w)
284=2 (2w+50)
divide both sides by 2
142=2w+50
subtract 50 on both sides
98=2w
divide both sides by 2
49=w
so width is 49, and we need to add 50 to it to find the length
l= 49 +50
l=99
If it's a negative exponent for example -6 the answer would be 1/x^-6. So if x is 10. Then 10^-6 is equal to 1/10^6 (One over ten to the power of 6 or One divided by 10 to the power six)