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2 years ago

Solve: the quantity 3x minus 15 divided by 2 = 4x

Mathematics

1 answer:

Anon25 [30]2 years ago

5 0

Answer:

x=-3

Step-by-step explanation:

(3x-15)/2 = 4x

Multiply each side by 2

(3x-15)/2 *2= 4x*2

3x-15 = 8x

Subtract 3x from each side

3x-15-3x = 8x-3x

-15 = 5x

Divide each side by 5

-15/5 = 5x/5

-3 =x

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A candlestick contains 5 pounds of silver. Suppose silver is worth $15 per ounce.

Evgen [1.6K]

Step-by-step explanation:

1 pound = 16 ounces

5 pound = 16 x 5 = 80

Cost per ounce = 15

Cost of 80 ounces = 15 x 80 = 1200

Option D is the correct answer

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2 years ago

Serena is single. She purchased her principal residence three years ago. She lived in the home until she sold it at a $300,000 g

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Answer: Long -term capital gain

Step-by-step explanation:

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2 years ago

There are 30 businesses with 4 executives each for the new office building. Each business needs one office for each of its

Zanzabum

Answer:

Step-by-step explanation:

B is the right one because the question says that every 4 executives can go into 1 office

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2 years ago

It is believed that as many as 23% of adults over 50 never graduated from high school. We wish to see if this percentage is the

JulijaS [17]

Answer:

1) n=48

2) n=298

3) n=426

Step-by-step explanation:

Previous concepts

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".

$p$ represent the real population proportion of interest

$\hat p$ represent the estimated proportion for the sample

n is the sample size required (variable of interest)

$z$ represent the critical value for the margin of error

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

Part 1

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by $\alpha=1-0.90=0.10$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=-1.64, z_{1-\alpha/2}=1.64$

The margin of error for the proportion interval is given by this formula:

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

And on this case we have that $ME =\pm 0.1$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

We can assume that the estimated proportion is 0.23 for the 25 to 30 group. And replacing into equation (b) the values from part a we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.1}{1.64})^2}=47.63$

And rounded up we have that n=48

Part 2

The margin of error on this case changes to 0.04 so if we use the same formula but changing the value for ME we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.04}{1.64})^2}=297.7$

And rounded up we have that n=298

Part 3

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by: