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3 years ago

This is due tomorrow PLZ HELP IMMEDIATELY

Mathematics

2 answers:

horsena [70]3 years ago

8 0

The value of X would be 9

Alexxandr [17]3 years ago

3 0

The answer is D.9 .......

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Historically, the mean yield of corn in the United States has been 120 bushels per acre with a standard deviation of 12. A surve

Illusion [34]

Answer:

$z=\frac{125-120}{\frac{12}{\sqrt{40}}}=2.64$

P-value

Since is a two sided test the p value would be:

$p_v =2*P(z>2.64)=0.0082$

And the best answer would be

B 0.0082

Step-by-step explanation:

Data given and notation

$\bar X=125$ represent the mean height for the sample

$\sigma=12$ represent the population standard deviation

$n=40$ sample size

$\mu_o =120$ represent the value that we want to test

$\alpha$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the true mean is 120 or not, the system of hypothesis would be:

Null hypothesis: $\mu = 120$

Alternative hypothesis: $\mu \neq 120$

If we analyze the size for the sample is > 30 and we know the population deviation so is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{125-120}{\frac{12}{\sqrt{40}}}=2.64$

P-value

Since is a two sided test the p value would be:

$p_v =2*P(z>2.64)=0.0082$

And the best answer would be

B 0.0082

4 0

3 years ago

the line joining A(a, 3) to B(2 -3) is perpendicular to the line joining C(10,1) to B. The value of a is?

RideAnS [48]

Well, first off, let's find what is the slope of BC

$\bf \begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
B&({{ 2}}\quad ,&{{ -3}})\quad 
% (c,d)
C&({{ 10}}\quad ,&{{ 1}})
\end{array}
\\\\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies 
\cfrac{{{ y_2}}-{{ y_1}}}{{{ x_2}}-{{ x_1}}}\implies \cfrac{1-(-3)}{10-2}\implies \cfrac{1+3}{10-2}
\\\\\\
\cfrac{4}{8}\implies \cfrac{1}{2}$

now, a line perpendicular to that one, will have a negative reciprocal slope, thus

$\bf \textit{perpendicular, negative-reciprocal slope for slope}\quad \cfrac{1}{2}\\\\
slope=\cfrac{1}{{{ 2}}}\qquad negative\implies -\cfrac{1}{{{ 2}}}\qquad reciprocal\implies - \cfrac{{{ 2}}}{1}\implies \boxed{-2}$

now, we know the slope "m" of AB is -2 then, thus

$\bf \begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
A&({{ a}}\quad ,&{{ 3}})\quad 
% (c,d)
B&({{ 2}}\quad ,&{{ -3}})
\end{array}
\\\\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies 
\cfrac{{{ y_2}}-{{ y_1}}}{{{ x_2}}-{{ x_1}}}\implies \cfrac{-3-3}{2-a}=\boxed{-2}
\\\\\\
\cfrac{-6}{2-a}=-2\implies -6=-4+2a\implies -2=2a\implies \cfrac{-2}{2}=a
\\\\\\
-1=a$

6 0

3 years ago

You invest $230 to start a sandwich stand and decide to charge $4.25 per sandwich. How much money will you make if you sell 75 s

Afina-wow [57]

You should do 4.25*75= 318.75
So you'll make $318.75

6 0

3 years ago

Read 2 more answers

The ice-cream truck had 112 ice-cream bars when it went out on its afternoon route. The driver sold 76 ice cream bars at the fir

Yuri [45]

I believe it would be 54 dollars.

Hope it helps,

3 0