Answer:
90 engines must be made to minimize the unit cost.
Step-by-step explanation:
Vertex of a quadratic function:
Suppose we have a quadratic function in the following format:

It's vertex is the point 
In which


Where

If a>0, the minimum value of the function will happen for 
C(x)=x²-180x+20,482
This means that 
How many engines must be made to minimize the unit cost?
x value of the vertex. So

90 engines must be made to minimize the unit cost.
The reasonable answer is D makes since
Answer:
Step-by-step explanation:
To graph this equation, start by plugging in different numbers for X and solve for Y.
For example: When x=0, y=0+3 ⇒ the coordinate is (0,3)
When x=1, y=1+3 ⇒ (1,4)
If you do this enough times, dotting each new coordinate then connecting them in a straight line, you will get your graph.
Answer:
12.895
Step-by-step explanation:
Standard deviation is a statistic that measures the dispersion of a sample. The sample standard deviation measures the spread of data distribution of the sample. It is usually used to estimate the population standard deviation.