Answer:
Step-by-step explanation:
We will use the work form of a quadratic to determine what a is...in fact we will write the equation for the whole thing in the process, because it's part of solving for a.
y = ±|a|(x - h)² + k
where x and y are from a coordinate point on the graph, h and k are the coordinates of the vertex, the absolute value of a indicates how steep or flat the graph is compared to the parent graph, and the ± is because a positive parabola opens up and a negative one opens upside down.
The vertex is (0, 9) and the coordinate point I chose to use is (3, 0). Filling those in and solving for a:
0 = ±|a|(3 - 0)² + 9 and
0 = ±|a|(3)² + 9 and
-9 = ±|a|9 and
-1 = ±|a| so a = 1. Because this is an upside down parabola the negative is out front, but a is independent of it. The correct choice is C. The quadratic function is
or in more detailed form:
The margin of error of the random selection is 0.29
The given parameters are:
--- the sample size
--- the standard deviation
--- the mean
--- the confidence level.
The margin of error (E) is calculated as follows:
So, we have:
The z-value for 90% confidence level is 1.645.
Substitute 1.645 for z
Take square roots
Multiply
Approximate
Hence, the margin of error is 0.29
Read more about margin of error at:
Step-by-step explanation:
the answer is in the above image
