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Alex777 [14]
3 years ago
8

Tom had 260 dollars to spend on 8 books. After buying them he had 12 dollars. How many much did each book cost?

Mathematics
1 answer:
fgiga [73]3 years ago
7 0
You will subtract 12 from 260 and get 248 then you will divide 248 by 8 and get 31 dollars spent per book.
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A coach is assessing the correlation between the number of hours spent practicing and the average number of points scored in a g
cricket20 [7]

Answer:

a) r=\frac{9(396)-(18)(153)}{\sqrt{[9(51) -(18)^2][9(3141) -(153)^2]}}=1  

We have a perfect linear relationship between the two variables

b) m=\frac{90}{15}=6  

Nowe we can find the means for x and y like this:  

\bar x= \frac{\sum x_i}{n}=\frac{18}{9}=2  

\bar y= \frac{\sum y_i}{n}=\frac{153}{9}=17  

And we can find the intercept using this:  

b=\bar y -m \bar x=17-(6*2)=5  

So the line would be given by:  

y=6 x +5  

c) For this case the slope indicates that for each increase of the number of hours in 1 unit we have an expected increase in the score about 6 units.

And the intercept 5 represent the minimum score expected for any game

Step-by-step explanation:

We have the following data:

Number of hours spent practicing (x) 0 0.5 1 1.5 2 2.5 3 3.5 4

Score in the game (y) 5 8 11 14 17 20 23 26 29

Part a

The correlation coefficient is given:

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=9 \sum x = 18, \sum y = 153, \sum xy = 396, \sum x^2 =51, \sum y^2 =3141  

r=\frac{9(396)-(18)(153)}{\sqrt{[9(51) -(18)^2][9(3141) -(153)^2]}}=1  

We have a perfect linear relationship between the two variables

Part b

m=\frac{S_{xy}}{S_{xx}}  

Where:  

S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}  

S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}  

With these we can find the sums:  

S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=51-\frac{18^2}{9}=15  

S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i){n}}=396-\frac{18*153}{9}=90  

And the slope would be:  

m=\frac{90}{15}=6  

Nowe we can find the means for x and y like this:  

\bar x= \frac{\sum x_i}{n}=\frac{18}{9}=2  

\bar y= \frac{\sum y_i}{n}=\frac{153}{9}=17  

And we can find the intercept using this:  

b=\bar y -m \bar x=17-(6*2)=5  

So the line would be given by:  

y=6 x +5  

Part c

For this case the slope indicates that for each increase of the number of hours in 1 unit we have an expected increase in the score about 6 units.

And the intercept 5 represent the minimum score expected for any game

5 0
3 years ago
Ram and his sister Kalpana win a prize of Rs 2000. They decide to share the prize in the ratio of their ages. Ram is 15 years ol
V125BC [204]

9514 1404 393

Answer:

  • Ram -- ₹1200
  • Kalpana -- ₹800

Step-by-step explanation:

Their age total is 15+10=25, so Ram will get 15/25 = 0.6 of the total. Kalpana will get the remaining 0.4 of the total.

  Ram receives 0.6 × ₹2000 = ₹1200

  Kalpana receives 0.4 × ₹2000 = ₹800

8 0
3 years ago
4) FRIDAY: An unknown quantity which is represented by a letter or a symbol is called _____
lukranit [14]

Answer:

A Variable

Step-by-step explanation:

Variables are used to mark an unknown value. Common math problems ask you to solve for it.

For example in 5x+23=45, 'x' is the variable.

A constant is a number without a variable.

<em>Brainilest Appreciated. </em>

8 0
3 years ago
A square in the board below and a letter in the word ATTENTION is chosen at
kolezko [41]

Answer:

4 /15

Step-by-step explanation:

From the number cube :

Count of Numbers greater than 4 = 16

Sample space of number cube = 20

P(number greater than 4) = 16 / 20 = 4/5

Word : ATTENTION

Count of letters in attention = 9

Count of T's in attention = 3

P(choosing T) = 3 / 9 = 1/3

P(greater than 4, then T) = 4/5 * 1/3 = 4 /15

5 0
2 years ago
1, -c/2 &lt; -1.5<br> 2. -y/2 &lt; 6<br> 3. -d/3 &gt; -9
irina1246 [14]

Answer:

um ight if your asking me if there are right i guess they are...

3 0
3 years ago
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