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kow [346]
3 years ago
11

The management of a supermarket wants to find if there is a relationship between the number of times a specific product is promo

ted on the intercom system in the store and the number of units of that product sold. To experiment the management selected a product and promoted it on the intercom system for seven days. The following table gives the number of times this product was promoted each day and the number of units sold.
Number of Promotions per Day Number of Units Sold per Day (hundreds)
15 11
22 22
42 30
30 26
18 17
12 15
38 23
a) With the number of promotions as an independent variable and the number of units sold as the dependent variable determine the least squares regression line. Give the equation of the line.
b) Compute r and r2. Explain their meaning.
c) Predict the number of units of this product sold on a day with 35 promotions.
d) Construct a 98% confidence interval for \beta .
e) Test at the 1% significant level that \beta is \beta \neq 0.
Mathematics
1 answer:
Degger [83]3 years ago
5 0

Answer:

15 11

Step-by-step explanation:

You might be interested in
3x+4y=38+5x-4y=-30/8x=8 this step works because of?
Alja [10]

Answer:

 Slope = -0.438/2.000 = -0.219

 x-intercept = 120/7 = 17.14286

 y-intercept = 120/32 = 15/4 = 3.75000

Step-by-step explanation:

Step  1  :

           15

Simplify   ——

           4

Equation at the end of step  1  :

                                   15          

 (3x + 4y) -  (((5x - 4y + 38) -  (—— • x)) -  8)  = 0

                                   4          

Step  2  :

Rewriting the whole as an Equivalent Fraction :

2.1   Subtracting a fraction from a whole

Rewrite the whole as a fraction using  4  as the denominator :

                    5x - 4y + 38     (5x - 4y + 38) • 4

    5x - 4y + 38 =  ————————————  =  ——————————————————

                         1                   4        

Equivalent fraction : The fraction thus generated looks different but has the same value as the whole

Common denominator : The equivalent fraction and the other fraction involved in the calculation share the same denominator

Adding fractions that have a common denominator :

2.2       Adding up the two equivalent fractions

Add the two equivalent fractions which now have a common denominator

Combine the numerators together, put the sum or difference over the common denominator then reduce to lowest terms if possible:

(5x-4y+38) • 4 - (15x)     5x - 16y + 152

——————————————————————  =  ——————————————

          4                      4      

Equation at the end of step  2  :

               (5x - 16y + 152)    

 (3x + 4y) -  (———————————————— -  8)  = 0

                      4            

Step  3  :

Rewriting the whole as an Equivalent Fraction :

3.1   Subtracting a whole from a fraction

Rewrite the whole as a fraction using  4  as the denominator :

        8     8 • 4

   8 =  —  =  —————

        1       4  

Adding fractions that have a common denominator :

3.2       Adding up the two equivalent fractions

(5x-16y+152) - (8 • 4)     5x - 16y + 120

——————————————————————  =  ——————————————

          4                      4      

Equation at the end of step  3  :

              (5x - 16y + 120)

 (3x + 4y) -  ————————————————  = 0

                     4        

Step  4  :

Rewriting the whole as an Equivalent Fraction :

4.1   Subtracting a fraction from a whole

Rewrite the whole as a fraction using  4  as the denominator :

               3x + 4y     (3x + 4y) • 4

    3x + 4y =  ———————  =  —————————————

                  1              4      

Adding fractions that have a common denominator :

4.2       Adding up the two equivalent fractions

(3x+4y) • 4 - ((5x-16y+120))     7x + 32y - 120

————————————————————————————  =  ——————————————

             4                         4      

Equation at the end of step  4  :

 7x + 32y - 120

 ——————————————  = 0

       4      

Step  5  :

When a fraction equals zero :

5.1    When a fraction equals zero ...

Where a fraction equals zero, its numerator, the part which is above the fraction line, must equal zero.

Now,to get rid of the denominator, Tiger multiplys both sides of the equation by the denominator.

Here's how:

 7x+32y-120

 —————————— • 4 = 0 • 4

     4    

Now, on the left hand side, the  4  cancels out the denominator, while, on the right hand side, zero times anything is still zero.

The equation now takes the shape :

  7x+32y-120  = 0

Equation of a Straight Line

5.2     Solve   7x+32y-120  = 0

Tiger recognizes that we have here an equation of a straight line. Such an equation is usually written y=mx+b ("y=mx+c" in the UK).

"y=mx+b" is the formula of a straight line drawn on Cartesian coordinate system in which "y" is the vertical axis and "x" the horizontal axis.

In this formula :

y tells us how far up the line goes

x tells us how far along

m is the Slope or Gradient i.e. how steep the line is

b is the Y-intercept i.e. where the line crosses the Y axis

The X and Y intercepts and the Slope are called the line properties. We shall now graph the line  7x+32y-120  = 0 and calculate its properties

Graph of a Straight Line :

 

Calculate the Y-Intercept :

Notice that when x = 0 the value of y is 15/4 so this line "cuts" the y axis at y= 3.75000

 y-intercept = 120/32 = 15/4  =  3.75000

Calculate the X-Intercept :

When y = 0 the value of x is 120/7 Our line therefore "cuts" the x axis at x=17.14286

 x-intercept = 120/7  = 17.14286

Calculate the Slope :

Slope is defined as the change in y divided by the change in x. We note that for x=0, the value of y is 3.750 and for x=2.000, the value of y is 3.313. So, for a change of 2.000 in x (The change in x is sometimes referred to as "RUN") we get a change of 3.313 - 3.750 = -0.438 in y. (The change in y is sometimes referred to as "RISE" and the Slope is m = RISE / RUN)

   Slope     = -0.438/2.000 = -0.219

Geometric figure: Straight Line

 Slope = -0.438/2.000 = -0.219

 x-intercept = 120/7 = 17.14286

 y-intercept = 120/32 = 15/4 = 3.75000

plz mark me as brainliest :)

3 0
3 years ago
I need help ASAP!!!!!!
swat32
Y=9/8x+7 is the equation for the graphed line
5 0
3 years ago
Read 2 more answers
A community bird-watching society makes and sells simple bird feeders to raise money for its conservation activities. The materi
valentina_108 [34]

Answer:

N(x) = 40 - 2x

P(x) = -2x² + 52 x - 240

maximum profit = 13

Step-by-step explanation:

given data

feeder cost = $6

average sell = 20 per week

price = $10 each

solution

we consider here price per feeder = x

and profit per feeder  id here formula   = x - 6

so that here

total profit will be

P (x)  = ( x - 6 ) Nx

here N(x) is number of feeders sold at price =  x

so formula for N (x)  is here

N(x) = 20 - 2 ( x - 10 )    

N(x) = 40 - 2x

so that

P(x) = (x-6) ( 40 - 2x)

P(x) = -2x² + 52 x - 240

since here

a = -2

b = 52

c = -240

a < 0

so quadratic function have maximum value of c - \frac{b^2}{4a}

so it will be

maximum value = -240 - \frac{52^2}{4(-2)}

maximum value = 98

so here maximum profit attained at

x = \frac{-b}{2a}

x = \frac{-52}{2(-2)}

x = 13

maximum profit = 13

3 0
3 years ago
Please help ASAP THIS IS MY FINAL QUESTION!!!! 20 points!!!!
givi [52]

Answer:

y= 1/2x-3

Step-by-step explanation:

2y - x = 8

First find the slope

2y = x+8

Divide by 2

2y/2 = x/2 +8/2

y = 1/2 x +4

The slope is 1/2  ( y=mx+b where m is the slope and b is the y intercept)

When lines are parallel they have the same slope)

Using y = mx+b

y =1/2x+b

Substituting the point (4,-1) into the equation

-1 =1/2(4)+b

-1 = 2+b

-3 =b

The equation of the line is

y= 1/2x-3

4 0
3 years ago
Help asap
anastassius [24]

Answer:

Step-by-step explanation:

The answer is 12 miles, if every inch is 3 miles on the map then 3x4=12.

7 0
3 years ago
Read 2 more answers
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