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Nimfa-mama [501]
3 years ago
6

Find the mean, standard deviation, and variance of Lucas's lunch expenditures. Round to the nearest thousandth.

Mathematics
1 answer:
olga2289 [7]3 years ago
7 0
So mean is pretty easy to calculate; you just add everything up and divide by the number of things you added. Variance is pretty tricky because it involves subtracting the mean from each number, squaring that, adding all of the numbers up, and then dividing by the number of things. Then standard deviation is just the square root of the variance. Although some might enjoy spending hours figuring these out (I actually had to take a class where we only did this and stuff like it), most of us who use statistical tests do not want to waste our time on it. It is for that reason that there are websites that will compute all of these and all you have to do is put in the numbers. A pretty good one is:

http://www.calculator.net/standard-deviation-calculator.html

This one will calculate these and almost any other tests you need.

Now to your problem, if we add all of them up and divide by N (the # of things added), then we will get a mean of (μ=$5.10). From this, we can do further descriptive statistics. Standard Variance of the sample was calculated to (s^2=0.254). If we take the square root of the variance, we get a standard deviation of (s=0.504). I hope that this helps you with this problem and I hope that I helped for future problems by introducing the variance and standard deviation calculator to you!
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Many elementary school students in a school district currently have ear infections. A random sample of children in two different
Marta_Voda [28]

Answer:

Step-by-step explanation:

The summary of the given data includes;

sample size for the first school n_1 = 42

sample size for the second school n_2  = 34

so 16 out of 42 i.e x_1 = 16 and 18 out of 34 i.e x_2 = 18 have ear infection.

the proportion of students with ear infection Is as follows:

\hat p_1 = \dfrac{16}{42} = 0.38095

\hat p_2 = \dfrac{18}{34}  =  0.5294

Since this is a two tailed test , the null and the alternative hypothesis can be computed as :

H_0 :p_1 -p_2 = 0 \\ \\ H_1 : p_1 - p_2 \neq 0

level of significance ∝ = 0.05,

Using the table of standard normal distribution, the value of z that corresponds to the two-tailed probability 0.05 is 1.96. Thus, we will reject the null hypothesis if the value of the test statistics is less than -1.96 or more than 1.96.

The test statistics for the difference in proportion can be achieved by using a pooled sample proportion.

\bar p = \dfrac{x_1 +x_2}{n_1 +n_2}

\bar p = \dfrac{16 +18}{42 +34}

\bar p = \dfrac{34}{76}

\bar p = 0.447368

\bar p + \bar  q = 1 \\ \\ \bar q = 1 -\bar  p \\  \\\bar q = 1 - 0.447368 \\ \\\bar q = 0.552632

The pooled standard error can be computed by using the formula:

S.E = \sqrt{ \dfrac{ \bar p \bar q}{ n_1} +  \dfrac{\bar p \bar p}{n_2} }

S.E = \sqrt{ \dfrac{  0.447368 *  0.552632}{ 42} +  \dfrac{ 0.447368 *  0.447368}{34} }

S.E = \sqrt{ \dfrac{  0.2472298726}{ 42} +  \dfrac{ 0.2001381274}{34} }

S.E = \sqrt{ 0.01177284105}

S.E = 0.1085

The test statistics is ;

z = \dfrac{\hat p_1 - \hat p_2}{S.E}

z = \dfrac{0.38095- 0.5294}{0.1085}

z = \dfrac{-0.14845}{0.1085}

z = - 1.368

Decision Rule: Since the test statistics is greater than the rejection region - 1.96 , we fail to reject the null hypothesis.

Conclusion: There is insufficient evidence to support the claim that a difference exists between the proportions of students who have ear infections at the two schools

5 0
3 years ago
Is he cute his name is arlo here is 5 points and brainliest
PtichkaEL [24]

Answer:

He is so cute

Step-by-step explanation:

5 0
2 years ago
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Good afternoon!
Vladimir [108]

9514 1404 393

Answer:

  5) 112°

  6) 40°

Step-by-step explanation:

5) The angle E or ? is half the sum of the intercepted arcs:

  ? = (130° +94°)/2 = 112°

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6) The angle D is half the difference of the intercepted arcs:

  ? = (135° -55°)/2 = 40°

8 0
2 years ago
What is the mode of 1 4 6 7 12 12 15
viktelen [127]

Answer:

The answer is 12

If you look at the set of data 12 is shown the most or there more then once when the others aren't

3 0
3 years ago
If x + 3y = 7 and y = 2, then x equals
Vaselesa [24]
The answer is one . 3 times 2 is 6. And you know 6+1 =7
5 0
2 years ago
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