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olga nikolaevna [1]
2 years ago
6

At a certain time of day, the angle of elevation is 40°. To the nearest foot, find the height of a tree whose shadow is 31 feet

long.
Mathematics
1 answer:
elena-s [515]2 years ago
7 0

Answer: Height of tree = 26 ft

Make a triangle ABC with 40 degrees angle. The shadow is the base of the triangle equals 31 feet.

Base = AC = 31

Perpendicular = CB = ?

Hypotenuse = AB

Using trigonometric equation

tan 40 (deg) = CB / AC

CB = Tan 40 x AC

CB = 0.83909 x 31

CB = 26.011

Thus the height of the tree = 26 ft

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is the distance between two consecutive maximum points, or two consecutive minimum points (these distances must be equal). Want to learn more about midline, amplitude, and period?

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The estimate of the population proportion should be within plus or minus 0.02, with a 90% level of confidence. The best estimate
Rudiy27

Answer:

The sample size required is 910.

Step-by-step explanation:

The confidence interval for population proportion is:

CI=\hat p\pm z_{ \alpha /2}\sqrt{\frac{\hat p(1-\hat p)}{n} }

The margin of error is:

MOE=z_{ \alpha /2}\sqrt{\frac{\hat p(1-\hat p)}{n} }

Given:

\hat p = 0.16\\MOE= 0.02\\Confidence\ level =0.90

The critical value of <em>z</em> for 90% confidence level is:

z_{\alpha /2}=z_{0.10/2}=z_{0.05}=1.645 *Use a standard normal table.

Compute the sample size required as follows:

MOE=z_{ \alpha /2}\sqrt{\frac{\hat p(1-\hat p)}{n} }\\0.02=1.645\times \sqrt{\frac{0.16(1-0.16)}{n} }\\n=\frac{(1.645)^{2}\times 0.16\times (1-0.16)}{(0.02)^{2}} \\=909.2244\\\approx910

Thus, the sample size required is 910.

5 0
3 years ago
The missing number in the series?
RoseWind [281]
A)48

Explanation:

2^3 - 2^2 = 8 - 4 = 4
3^3 - 3^2 = 27 - 9 = 18
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5^3 - 5^2 = 125 - 25 = 100
6^3 - 6^2 = 216 - 36 = 180
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nathan smiled at 50 people one day and recorded that 36 people smiled back at him.Based on his observations how many people shou
Olegator [25]

Given :

Nathan smiled at 50 people one day and recorded that 36 people smiled back at him.

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How many people should Nathan expect to return a smile if he smiles at 650 people over a period of time.

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R = \dfrac{36}{50}

Now, it is given that we have to use the given conditions.

Therefore, ratio will be same :

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Therefore, number of smiles Nathan expect to return is 468.

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3 years ago
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