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.
You first set it up as long division.
Second you would find out how many times 6 goes into 67, so count by 6's until you get close 67.
Third once you get that number you write it on top of the long division and then you would subtract whatever that number is below which is 66 because 6 * 11= 66.
So then you would subtract 67 minus 66 which would be 1. Then go from there and you'll get your answer.
Hope this helps!
According to empirical rule, the area under the normal distribution or "bell-shaped curve", when plotted as a function of the z-parameter can be defined in terms of percentages.
The z-parameter (or z-score) is defined as

where
x = value of random variable,
μ = the mean,
σ = standard deviation,
The total area under the curve = 1.
The curve below shows that within 2 standard deviations from the mean, the total area under the curve is 95% of the total area.
Answer:
95%
-3z - (-z - 2)
In order to find the expression equivalent to our given expression, we have to simplify our given expression :)
-3z + z + 2
**Remember : the "z" and "2" become a positive because a negative times a negative is always a positive!**
Now, add like terms.
(-3z + z) + 2
Simplify.
-2z + 2
Look at our given answer choices.
Our answer is c. -2z + 2
~Hope I helped!~
Answer:
4
Step-by-step explanation: