Answer:
(-5,-13)
Step-by-step explanation:
Find the vertex of the parabola y=1/5x^2+2x−8.
In this equation a=15 and b = 2.
x= -2/2(1/5) = -2/2/5 = -2/1 * 5/2 = -5
Substitute −5 into the equation y=1/5x^2+2x−8
y=1/5(−5)^2+2(−5)−8
y=5−10−8
y=−13
The vertex is (−5 , −13)
Answer:
Standard deviation 46.3
Step-by-step explanation:
A 28% of the distribution is equivalent to a z score of -0.5828, you can use a z table to find that.
Z score is calculated as follows:

x is the number being evaluated
μ is the mean
σ is the standard deviation
And it is used to calculate how many standard deviations you are from the mean of the sample.
Replacing with the known information you can calculate the standard deviation:

L=n-2, W=4+L=n+2
A=LW, since L=n-2 and W=n+2 we have:
A=(n-2)(n+2) so it could be this expression or the expansion
A=n^2-4