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2 years ago

One number is 3 more than another. The difference between their square is 63. What are the numbers?

1 answer:

7 0

X = y + 3
x^2 - y^2 = 63

(y + 3)^2 - y^2 = 63
(y + 3)(y + 3) - y^2 = 63
y^2 + 6y + 9 - y^2 = 63
6y + 9 = 63
6y = 54
y = 54/6
y = 9

x = y + 3
x = 9 + 3
x = 12

check...
x^2 - y^2 = 63 x = y + 3
12^2 - 9^2 = 63 12 = 9 + 3
144 - 81 = 63 12 = 12 (correct)
63 = 63 (correct)

ur 2 numbers are 9 and 12

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What is the slope of this line

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Step-by-step explanation:

rise/run = slope

As it goes to the left or adds by one, it goes up by 4

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3 years ago

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At a recent county fair, you observed that at one stand people's weight was forecasted, and were surprised by the accuracy (with

MatroZZZ [7]

Answer:

a)Slope: $\hat \beta_1 =\frac{7625.9}{1248.9}=6.106$

Intercept: $\hat \beta_o = 157.955 -6.106 (69.686)=-267.548$

b) $r=\frac{7625.9}{\sqrt{[1248.9][94228.8]}}=0.657$

And the determination coeffecient is $r^2 = 0.657^2 =0.432$

Step-by-step explanation:

Data given and definitions

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.

The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"

When we conduct a multiple regression we want to know about the relationship between several independent or predictor variables and a dependent or criterion variable.

n=110, $\sum x_i y_i = \sum (X-\bar X)(Y-\bar Y) =7625.9,\sum x^2_i=\sum (x-\bar x)^2 =1248.9 , sum y^2_i=\sum(y-\bar y)^2 =94228.8$

$\sum Y_i =17375 , \sum X_i = 7665.5$

Part a

The slope is given by this formula:

$\hat \beta_1 =\frac{\sum (x-\bar x) (y-\bar y)}{\sum (x-\bar x )^2}$

If we replace we got:

$\hat \beta_1 =\frac{7625.9}{1248.9}=6.106$

We can find the intercept with the following formula

$\hat \beta_o = \bar y -\hat \beta_1 \bar x$

We can find the average for x and y like this:

$\bar X=7665.5/110 =69.686, \bar y= 17375/110=157.955$

And replacing we got:

$\hat \beta_o = 157.955 -6.106 (69.686)=-267.548$

Part b

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

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

For our case we have this:

n=110, $\sum x_i y_i = \sum (X-\bar X)(Y-\bar Y) =7625.9,\sum x^2_i=\sum (x-\bar x)^2 =1248.9 , sum y^2_i=\sum(y-\bar y)^2 =94228.8$

So we can find the correlation coefficient replacing like this:

$r=\frac{7625.9}{\sqrt{[1248.9][94228.8]}}=0.657$

And the determination coeffecient is $r^2 = 0.657^2 =0.432$

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3 years ago

A water storage tank is in the shape of a cone with the pointed end down. If the radius is 21 feet and the depth of the tank is

andre [41]

The volume of the water storage tank is the amount of space in it

The volume of the water storage tank is 6468 cubic feet

<h3>How to determine the volume?</h3>

The given parameters are:

Radius (r) = 21 feet

Height (h) = 14 feet

The shape of the water storage tank is a cone.

And the volume of a cone is:

V = 1/3πr^2h

So, we have:

V = 1/3 * 22/7 * 21^2 * 14

This gives

V = 6468

Hence, the volume of the water storage tank is 6468 cubic feet