Answer:
a) 0.1587
b) 0.0475
c) 0.7938
Step-by-step explanation:
Let's start defining our random variable.
X : ''Thickness (in mm) of ancient prehistoric Native American pot shards discovered in a Hopi village''
X is modeled as a normal random variable.
X ~ N(μ,σ)
Where μ is the mean and σ is the standard deviation.
To calculate all the probabilities, we are going to normalize the random variable X.
We are going to call to the standard normal distribution ''Z''.
[(X - μ) / σ] ≅ Z
We normalize by subtracting the mean to X and then dividing by standard deviation.
We can find the values of probabilities for Z in a standard normal distribution table.
We are going to call Φ(A) to the normal standard cumulative distribution evaluated in a value ''A''
a)

Φ(-1) = 0.1587
b)


1 - Φ(1.666) = 1 - 0.9525 = 0.0475
c)

Φ(1.666) - Φ(-1) = 0.9525 - 0.1587 = 0.7938
Because if you don’t put anything they won’t hire you
This is a stupid question. The teacher who asked this needs to go back to school.
A = x⁴ - 9y²
That's going to be a number. As long as it's positive we can choose any length for our rectangle L and we can compute the width by W=A/L. So the correct answer is the dimensions are L by (x⁴ - 9y²)/L.
They don't want the correct answer. They want you to factor this expression. We'll do it, but don't believe for a second this factoring somehow constrains the possible dimensions of some rectangle.
We use the difference of two squares, a²-b² = (a+b)(a-b)
A = x⁴ - 9y² = (x²)² - (3y)² = (x²+3y)(x²-3y)
Answer: x²+3y by x²-3y