ANSWER:
2.33 foot
STEP-BY-STEP EXPLANATION:
We can calculate the distance from the staircase to the wall, by means of the trigonometric cosine ratio, which is the following:

Replacing and solving for x:

The distance would be 2.33 foot
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Equation
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y = -3x - 9
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Option 1
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If I substitute x = -9, I should get y = 0
When x = -9
y = -3 (-9) - 9
= 18 (I did not get 0, wrong)
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Option 2
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If I substitute x = -3, I should get y = 0
y = -3(-3) - 9
y = 9 - 9
y = 0 (Yes, I got 0, correct)
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Option 3
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If I substitute x = 0, I should get y = -3
y = -3 (0) - 9
y = 0 - 9
y = -9 (I did not get -3, wrong)
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Option 4
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If I substitute x = 0, I should get y = -9
y = -3 (0) - 9
y = 0 - 9
y = -9 (Yes, I got -9, correct)
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Answer: (-3, 0) and (0, 9) are ordered pairs of the equation (Answer B, D)
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Answer:

Step-by-step explanation:
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The population proportion have the following distribution

So under the null hypothesis the mean for the population proportion is p

And the standard deviationis given by:

Constants are numbers alone with no variables.
The constants are: 12, -3.7, 1/3