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2 years ago

7

A tower casts a shadow that is 60 feet long when the angle of elevation of the sun is 65˚. How tall is the tower? Round answer t

o the nearest whole number correctly!

1 answer:

r-ruslan [8.4K]2 years ago

3 0

Answer: Tthe tower is 129 feet tall.

Step-by-step explanation:

According to trigonometry in a right triangle:

$\tan\theta =\dfrac{\text{Side opposite to }\theta}{\text{Side adjacent to }\theta}$

Let x be the height of the tower.

Given , $\theta=65^{\circ}$

Since tower stands vertical to the ground, that means it is making a right triangle with the shadow.

$\tan 65^{\circ}=\dfrac{x}{60}\\\\\Rightarrow\ 2.1445=\dfrac{x}{60}\ \ \text{[Using calculator]}\\\\\Rightarrow x= 2.1445\times60=128.67\approx129\text{ feet}$

Hence, the tower is 129 feet tall.

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The CPA Practice Advisor reports that the mean preparation fee for 2017 federal income tax returns was $273. Use this price as t

skad [1K]

Answer:

a) 0.6212 = 62.12% probability that the mean price for a sample of 30 federal income tax returns is within $16 of the population mean.

b) 0.7416 = 74.16% probability that the mean price for a sample of 50 federal income tax returns is within $16 of the population mean.

c) 0.8804 = 88.04% probability that the mean price for a sample of 100 federal income tax returns is within $16 of the population mean.

d) None of them ensure, that one which comes closer is a sample size of 100 in option c), to guarantee, we need to keep increasing the sample size.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

The CPA Practice Advisor reports that the mean preparation fee for 2017 federal income tax returns was $273. Use this price as the population mean and assume the population standard deviation of preparation fees is $100.

This means that $\mu = 273, \sigma = 100$

A) What is the probability that the mean price for a sample of 30 federal income tax returns is within $16 of the population mean?

Sample of 30 means that $n = 30, s = \frac{100}{\sqrt{30}}$

The probability is the p-value of Z when X = 273 + 16 = 289 subtracted by the p-value of Z when X = 273 - 16 = 257. So

X = 289

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{289 - 273}{\frac{100}{\sqrt{30}}}$

$Z = 0.88$

$Z = 0.88$ has a p-value of 0.8106

X = 257

$Z = \frac{X - \mu}{s}$

$Z = \frac{257 - 273}{\frac{100}{\sqrt{30}}}$

$Z = -0.88$

$Z = -0.88$ has a p-value of 0.1894

0.8106 - 0.1894 = 0.6212

0.6212 = 62.12% probability that the mean price for a sample of 30 federal income tax returns is within $16 of the population mean.

B) What is the probability that the mean price for a sample of 50 federal income tax returns is within $16 of the population mean?

Sample of 30 means that $n = 50, s = \frac{100}{\sqrt{50}}$

X = 289

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{289 - 273}{\frac{100}{\sqrt{50}}}$

$Z = 1.13$

$Z = 1.13$ has a p-value of 0.8708

X = 257

$Z = \frac{X - \mu}{s}$

$Z = \frac{257 - 273}{\frac{100}{\sqrt{50}}}$

$Z = -1.13$

$Z = -1.13$ has a p-value of 0.1292

0.8708 - 0.1292 = 0.7416

0.7416 = 74.16% probability that the mean price for a sample of 50 federal income tax returns is within $16 of the population mean.

C) What is the probability that the mean price for a sample of 100 federal income tax returns is within $16 of the population mean?

Sample of 30 means that $n = 100, s = \frac{100}{\sqrt{100}}$

X = 289

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{289 - 273}{\frac{100}{\sqrt{100}}}$

$Z = 1.6$

$Z = 1.6$ has a p-value of 0.9452

X = 257

$Z = \frac{X - \mu}{s}$

$Z = \frac{257 - 273}{\frac{100}{\sqrt{100}}}$

$Z = -1.6$

$Z = -1.6$ has a p-value of 0.0648

0.9452 - 0.0648 =

0.8804 = 88.04% probability that the mean price for a sample of 100 federal income tax returns is within $16 of the population mean.

D) Which, if any of the sample sizes in part (a), (b), and (c) would you recommend to ensure at least a .95 probability that the same mean is withing $16 of the population mean?

None of them ensure, that one which comes closer is a sample size of 100 in option c), to guarantee, we need to keep increasing the sample size.

6 0

2 years ago

The weights (in ounces) of 14 different apples are shown below. Find Q 3. 5.7 5.5 4.7 4.4 6.8 5.7 5.5 6.9 6.0 4.4 5.7 6.9 4.4 4.

elena55 [62]

I Think 5.7 I’m Not Sure

6 0

3 years ago

Pls Help meeeee UWU (im gonna die)

Ronch [10]

Answer:

10

Step-by-step explanation:

When you sub in the numbers you get 20 divided by 2

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3 years ago

Michael bought 3 12 gallons of white paint at $17.50 each gallon and 134 gallons of blue paint at $19.00 each gallon. What was h

lutik1710 [3]

312 gallons of white paint, $17.50 each gallon

134 gallons of blue paint, $19 for each gallon

312 x 17.50 = $5,460

134 x 19 = $2,546

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3 years ago

An insurance agent receives 15% of the cost of each insurance policy she sells

HACTEHA [7]

In this question there are several important information's provided. Using these information's it is easy to get the answer to the question asked. Firstly it is already informed that the insurance agent gets a commission of 15% of the policy price for every policy sold. The agent sells a policy of $300.
Now we can write the equation as:
15% of $300 = [(15/100) * 300] dollars
= ( 15 * 3) dollars
= 45 dollars
So the agent gets a commission of $45 for selling a policy worth $300

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3 years ago