A recipe of 3 1/4 cups of flour serves 15 people. Write a proportion tp find the number of servings that 4 1/2 cups of flour mak
1 answer:
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Answer:
The depth of the reflector is 0.84 feet
Step-by-step explanation:
<em>(See the figure below)</em>
The equation of a parabola centered at the origin with an axis of symmetry on y-axis is:
(1)
With p the distance from the origin to the focus using p=6, the equation (1) of the parabola becomes:
(2)
Note that the point B is on the parabola, so this point should satisfy the parabola equation (2) that allow us to use the value x=4.5 to find the y value associated to it, that it is the depth (h) of the reflector:
, solving for y
Using the z-distribution, it is found that a sample of 171 should be selected.
<h3>What is a z-distribution confidence interval?</h3>The confidence interval is:
The margin of error is:
In which:
is the sample mean.
- z is the critical value.
- n is the sample size.
is the standard deviation for the population.
For this problem, the parameters are:
Hence we solve for n to find the needed sample size.
n = 170.7.
Rounding up, a sample of 171 should be selected.
More can be learned about the z-distribution at brainly.com/question/25890103
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