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3 years ago

Simplify (8z - 10) ÷ (-2) + 5(z - 1). plz show work

Mathematics

1 answer:

Bess [88]3 years ago

6 0

(8z - 10) ÷ (-2) + 5(z - 1) = 8z - 10 ÷ -2 + 5z - 5 = 8z + 5 + 5z - 5 = 13z

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Five observations taken for two variables follow.

I am Lyosha [343]

Answer:

a) Figure attached

b) If we see the scatter plot we can conclude that the possible relation between x and y is linear and with a positive correlation since when the values of x increases the values for y increases as well.

c) $Cov (X,Y) = \frac{\sum_{i=1}^n (x_i -\bar X)(y_i -\bar Y)}{n-1}$

We can find the numerator like this:

$\sum_{i=1}^5 (6-16)(6-10)+(11-16)(9-10)+(15-16)(6-10)+(21-16)(17-10)+(27-16)(12-10)=106$

And then:

$Cov(X,Y) = \frac{106}{5-1}=26.5$

d) $r=\frac{5(906)-(80)(50)}{\sqrt{[5(1552) -(80)^2][5(586) -(50)^2]}}=0.693$

Step-by-step explanation:

Part a

For this part we use excel in order to create the scatterplot and we got the result on the figure attached.

Part b

If we see the scatter plot we can conclude that the possible relation between x and y is linear and with a positive correlation since when the values of x increases the values for y increases as well.

Part c

The sample covariance is defined as:

$Cov (X,Y) = \frac{\sum_{i=1}^n (x_i -\bar X)(y_i -\bar Y)}{n-1}$

We can find the numerator like this:

$\sum_{i=1}^5 (6-16)(6-10)+(11-16)(9-10)+(15-16)(6-10)+(21-16)(17-10)+(27-16)(12-10)=106$

And then:

$Cov(X,Y) = \frac{106}{5-1}=26.5$

Part d

The correlation coefficient is a "statistical measure that calculates the strength of the relationship between the relative movements of two variables". It's denoted by r and its always between -1 and 1.

And in order to calculate the correlation coefficient we can use this formula:

$r=\frac{n(\sum xy)-(\sum x)(\sum y)}{\sqrt{[n\sum x^2 -(\sum x)^2][n\sum y^2 -(\sum y)^2]}}$

For our case we have this:

n=5 $\sum x = 80, \sum y = 50, \sum xy = 906, \sum x^2 =1552, \sum y^2 =586$

$r=\frac{5(906)-(80)(50)}{\sqrt{[5(1552) -(80)^2][5(586) -(50)^2]}}=0.693$

So then the correlation coefficient would be r =0.693

3 0

3 years ago

In the after school Dena, Shawn, and Amanda knit scarfs that are the same size with yellow, white, and blue yarn. Denas scarf is

jenyasd209 [6]

Answer:

$\frac{8}{20}$

Step-by-step explanation:

We have been given that in the after school Dena, Shawn, and Amanda knit scarfs that are the same size with yellow, white, and blue yarn. Denas scarf is 2/5 yellow, Shawn's scarf is 3/5 , and Amanda's scarf is 3/4 yellow.

To make Amanda's argument true, let us compare each fraction by making a common denominator.

We can see that least common denominator of each fraction would be 20.

$\text{Dena's scarf}=\frac{2}{5}\Rightarrow\frac{2*4}{5*4}=\frac{8}{20}$