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alexira [117]
3 years ago
6

How do I work this out?

Mathematics
2 answers:
marin [14]3 years ago
4 0
Area of a full circle is: PI x r^2

so full circle is 4^2 x PI = 16PI

the shaded part is 3/4 of the circle

16 x 3/4 = 12
 so 12 PI ft^2 is shaded

Vikentia [17]3 years ago
3 0
First, find the area of the circle as a whole. Then find the percentage or fraction of that area.

STEP ONE

As you probably know, you use this formula to find the area of any circle.

A=\pir^2

We know what the radius is, so substitute the 4 for the r in the formula.

A=4^2\pi

Simplify.

A=4^2\pi
A=16\pi

STEP TWO

Now that we know what the area of the circle is as a whole, let's find the fraction of that area. We want to the know the area of the shaded part.

Multiply the area by 3/4.

(16\pi)(3/4)
(48\pi)/4
12\pi

So, the answer is the first option.
You might be interested in
Find x. problem is in picture
Masja [62]

Answer:

x=21

Step-by-step explanation:

We know that C is a right angle, which means that x + 3x+6 = 90

4x+6=90\\4x=84\\x=21

Have a nice day. hope I helped please rate brainliest!

3 0
3 years ago
g If a hypothesis test with a significance level of α rejects H0: μ1=μ2 in favor of Ha: μ1≠μ2, then thecorresponding (1- α)% con
Effectus [21]

Answer:

The statement, (1- <em>α</em>)% confidence interval for (μ₁ - μ₂) does not contain zero is TRUE.

Step-by-step explanation:

The hypothesis for a test is defined as follows:

<em>H</em>₀: μ₁ = μ₂ vs. <em>H</em>ₐ: μ₁ ≠ μ₂

It is provided that the test was rejected st the significance level <em>α</em>%.

If a decision is to made using the confidence interval the conditions are:

If the null hypothesis value is not included in the (1 - <em>α</em>)% confidence interval then the null hypothesis will be rejected and vice versa.

In this case the null hypothesis value is:

<em>H</em>₀: μ₁ - μ₂ = 0.

If the value 0 is not included in the (1 - <em>α</em>)% confidence interval for the difference between two means, then the null hypothesis will be rejected.

Thus the statement, (1- <em>α</em>)% confidence interval for (μ1- μ2) does not contain zero is TRUE.

5 0
3 years ago
Simplify the expression: –3(3 + 2n)
noname [10]

Answer:

-9 - 6n is the answer

8 0
3 years ago
Read 2 more answers
I need help on this plz i don’t understand the question
AnnZ [28]

We know that the area of a circle in terms of π will be πr². However the area with respect to the diameter will be a different story. The first step here is to find a function relating the area and diameter of any circle --- ( 1 )

For any circle the diameter is 2 times the radius,

d = 2r

Therefore r = d / 2, which gives us the following formula through substitution.

A = π(d / 2)² = πd² / 4

<u>Hence the area of a circle as the function of it's diameter is A = πd² / 4. You can also say f(d) = πd² / 4.</u>

Now we can substitute " d " as 4, solving for the area ( A ) or f(4) --- ( 2 )

f(4) = π(4)² / 4 = 16π / 4 = 4π - <u>This makes the area of circle present with a diameter of 4 inches, 4π.</u>

3 0
3 years ago
A fast food restaurant executive wishes to know how many fast food meals adults eat each week. They want to construct a 98% conf
adelina 88 [10]

Answer:

n=(\frac{2.326(1.1)}{0.07})^2 =1336.006 \approx 1337

So the answer for this case would be n=1337 rounded up to the nearest integer

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".

\bar X represent the sample mean for the sample  

\mu population mean (variable of interest)

\sigma=1.1 represent the population standard deviation

n represent the sample size  

Solution to the problem

The margin of error is given by this formula:

ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}    (a)

And on this case we have that ME =0.07 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

n=(\frac{z_{\alpha/2} \sigma}{ME})^2   (b)

The critical value for 98% of confidence interval now can be founded using the normal distribution. And in excel we can use this formula to find it:"=-NORM.INV(0.01;0;1)", and we got z_{\alpha/2}=2.326, replacing into formula (b) we got:

n=(\frac{2.326(1.1)}{0.07})^2 =1336.006 \approx 1337

So the answer for this case would be n=1337 rounded up to the nearest integer

3 0
3 years ago
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