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3 years ago

20=8+3(12+4x) Please help It's really hard

2 answers:

5 0

20 = 8 + 3(12 + 4x)

First, distribute 3:

20 = 8 + 36 + 12x

Add:

20 = 44 + 12x

Subtract 44 to both sides:

-24 = 12x

Divide 12 to both sides:

x = -2

nataly862011 [7]3 years ago

4 0

So first, you have to remember the order of operations. That means that whatever is in the parentheses is what has to be done first
However, because one of the numbers in the parentheses is a variable and the other isn't, we can distribute instead
Therefore, 3(12+4x) distributes by multiplying the 3 into both numbers in the parentheses. So we get 36+12x
Now the equation is 20=8+36+12x
Now, bring all numbers without variables on the left side

20-8-36=8-8+36-36+12x
20-8-36=12x

Now simplify

20-8-36=12x
12-36=12x
-24=12x

Divide both sides by 12, and you get x=-2

Hope this helped!!! :D

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You are interested in estimating the the mean age of the citizens living in your community. In order to do this, you plan on con

AlladinOne [14]

Using the z-distribution, a sample size of 180 is needed for the estimate.

<h3>What is a z-distribution confidence interval?</h3>

The confidence interval is:

$\overline{x} \pm z\frac{\sigma}{\sqrt{n}}$

The margin of error is given by:

$M = z\frac{\sigma}{\sqrt{n}}$

In which:

$\overline{x}$ is the sample mean.

z is the critical value.

n is the sample size.

$\sigma$ is the standard deviation for the population.

In this problem, we have a 98% confidence level, hence $\alpha = 0.98$ , z is the value of Z that has a p-value of $\frac{1+0.98}{2} = 0.99$ , so the critical value is z = 2.327.

The population standard deviation is of $\sigma = 23$ , and to find the sample size, we have to solve for n when M = 4.

Hence:

$M = z\frac{\sigma}{\sqrt{n}}$

$4 = 2.327\frac{23}{\sqrt{n}}$

$4\sqrt{n} = 2.327 \times 23$

$\sqrt{n} = \frac{2.327 \times 23}{4}$

$(\sqrt{n}) = \left(\frac{2.327 \times 23}{4}\right)^2$

n = 179.03.

Rounding up, as a sample size of 179 would result in an error slightly above 4, a sample of 180 is needed.

More can be learned about the z-distribution at brainly.com/question/25890103

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8 0

2 years ago

You deposit $650 in a savings account. How long does it take an account with an annual interest rate of 5% to earn $178.25 in in

laiz [17]

Answer:

It takes an account 5.4 years to earn $178.25 in interest with an annual interest rate of 5%.

Step-by-step explanation:

You can use the following formula to calculate the time it takes an account to earn a certain amount in interest:

t=(1/r)*((F/P)-1), where:

t= time

r= rate of interest= 5%

F= future value= 650+178.25=828.25

P= present value= 650

Now, you can replace the values on the formula:

t=(1/0.05)*((828.25/650)-1)

t=20*0.27

t=5.4

According to this, the answer is that it takes an account 5.4 years to earn $178.25 in interest with an annual interest rate of 5%.

3 0

3 years ago

The height of a hill, h(x), in a painting can be written as a

matrenka [14]

Answer:

First option: $6\ inches$

Step-by-step explanation:

<h3> The complete exercise is: "The height of a hill, h(x), in a painting can be written as a function of x, the distance from the left side of the painting. Both h(x) and x are measured in inches $h(x) = -\frac{1}{5}(x)(x -13)$ . What is the height of the hill in the painting 3 inches from the left side of the picture?</h3>

You have the following function provided in the exercise:

$h(x) = -\frac{1}{5}(x)(x -13)$

You know that $h(x)$ represents the height of the hill (in inches) and "x" represents the distance from the left side of the painting (in inches)