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3 years ago

Help i was sick and missed this lesson

Mathematics

1 answer:

AleksandrR [38]3 years ago

5 0

1.
x - 2y = -19
5x + 2y = 1 /+

6x = -18 / 6
x = -3

-3 - 2y = -19
-2y = -16. / ÷(-2)
y = 8

2.
3x + 4y = 18
-2x + 4y = 8 / ×(-1)

3x + 4y = 18
2x - 4y = -8 /+

5x = 10 / ÷5
x = 2

3 × 2 + 4y = 18
6 + 4y = 18 / -6
4y = 12 / ÷4
y = 3

3.
2x + y = 3
-x + 3y = -12 / ×2

2x + y = 3
-2x + 6y = -24 /+

7y = -21 / ÷7
y = -3

2x - 3 = 3 / +3
2x = 6 / ÷2
x = 3

Hit me up in comments if anything is unclear.

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Answer:

Let's assume the following data:

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Number of Bids (Y) 12 13 15 16 18

For our case we have this:

n=10 $\sum x = 172, \sum y = 74, \sum xy = 2623, \sum x^2 =6194, \sum y^2 =1118$

$r=\frac{5(2623)-(172)(74)}{\sqrt{[5(6194) -(172)^2][5(1118) -(74)^2]}}=0.974$

So then the correlation coefficient would be r =0.974

Step-by-step explanation:

Previous concepts

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.

Solution to the problem

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

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

Let's assume the following data

Price in Dollars (X) 26 29 32 38 47

Number of Bids (Y) 12 13 15 16 18

For our case we have this:

n=10 $\sum x = 172, \sum y = 74, \sum xy = 2623, \sum x^2 =6194, \sum y^2 =1118$

$r=\frac{5(2623)-(172)(74)}{\sqrt{[5(6194) -(172)^2][5(1118) -(74)^2]}}=0.974$

So then the correlation coefficient would be r =0.974

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3 years ago