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Lunna [17]
3 years ago
11

The radius of a circle is 9 inches. What is the area ? Give the exact answer in simplest form

Mathematics
1 answer:
weqwewe [10]3 years ago
8 0
A= πr^2
r=9
A= π(9)^2
A= 9x9=81
A=81π

In case that you have to use π
Multiply π(3.14)
3.14 times 81=254.34
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(_12)+7 what is solution ​
Mama L [17]

Answer:

Step-by-step explanation:

-12 + 7= - 5

6 0
2 years ago
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The sum of two numbers is 75. The second number is 3 less than twice the first
Mandarinka [93]

Answer:

\large{\textbf{The two numbers are: 26 and 49}.\\}

Step-by-step explanation:

\large{\textup{assume the two numbers are $x$ and $y$.}}\\\large{\textup{The given sentences are written in mathematical terms as follows:}\\$$ x + y =  75  \hspace{25mm} (1)$$ $$ y = 2x - 3 \hspace{25mm} (2) $$  \\\textup{Substituting $(2)$ in $(1)$,}\\\begin{align*} &  \implies x + 2x - 3 = 75  \\& \implies 3x = 78 \\& \implies x = 26\end{align*}\textup{Substituting $x$ in $(1), \hspace{5mm} y = 49$} }

7 0
2 years ago
Bob Nale is the owner of Nale’s Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his custom
ira [324]

Answer:

a) The best estimator for the population mean is given by the sample mean \hat \mu = \bar X = 5.70

b) The 99% confidence interval would be given by (4.969;6.431)    

c) We are 99% confident that the true mean for th number of gallons of gasoline  sold to his customers is between 4.969 and 6.431.

Step-by-step explanation:

1) 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=1.9 represent the population standard deviation

n=45 represent the sample size  

2) Part a

The best estimator for the population mean is given by the sample mean \hat \mu = \bar X = 5.70

3) Part b. Develop a 99 percent confidence interval for the population mean.

The confidence interval for the mean is given by the following formula:

\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}   (1)

Since the Confidence is 0.95 or 95%, the value of \alpha=0.01 and \alpha/2 =0.005, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that z_{\alpha/2}=2.58

Now we have everything in order to replace into formula (1):

5.7-2.58\frac{1.9}{\sqrt{45}}=4.969    

5.7+2.58\frac{1.9}{\sqrt{45}}=6.431

So on this case the 99% confidence interval would be given by (4.969;6.431)    

4) Part c. Interpret the meaning of part (b).

On this case we can say this: We are 99% confident that the true mean for th number of gallons of gasoline  sold to his customers is between 4.969 and 6.431.

4 0
3 years ago
F = 2x + y<br> 3x + 5y = 45 x20 and y20<br> 2x + 4&lt;32
ipn [44]

Answer:

a

Step-by-step explanation:

6 0
3 years ago
SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SA
kotegsom [21]

Answer:

I should use at least 304 students

Step-by-step explanation:

Margin error (E) = t × sd/√n

E = 40

sd = 300

confidence level (C) = 98% = 0.98

significance level = 1 - C = 1 - 0.98 = 0.02 = 2%

t-value corresponding to 2% significance level and infinity degree of freedom is 2.326

n = (t×sd/E)^2 = (2.326×300/40)^2 = 17.445^2 = 304 (to the nearest integer)

3 0
3 years ago
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