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3 years ago

What are the numbers x+ y = 17 x - y= 7

1 answer:

8 0

X = 12 and y = 5

I found this out by starting out with x = 10 and y = 7 (because 10 + 7 equals 17), and escalating while trying out every number with both equations.

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An experiment was conducted to observe the effect of an increase in temperature on the potency of an antibiotic. Three 1-ounce p

ludmilkaskok [199]

Answer:

a) $y=-0.317 x +46.02$

b) Figure attached

c) $S^2=\hat \sigma^2=MSE=\frac{190.33}{10}=19.03$

Step-by-step explanation:

We assume that th data is this one:

x: 30, 30, 30, 50, 50, 50, 70,70, 70,90,90,90

y: 38, 43, 29, 32, 26, 33, 19, 27, 23, 14, 19, 21.

a) Find the least-squares line appropriate for this data.

For this case we need to calculate the slope with the following formula:

$m=\frac{S_{xy}}{S_{xx}}$

Where:

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

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

So we can find the sums like this:

$\sum_{i=1}^n x_i = 30+30+30+50+50+50+70+70+70+90+90+90=720$

$\sum_{i=1}^n y_i =38+43+29+32+26+33+19+27+23+14+19+21=324$

$\sum_{i=1}^n x^2_i =30^2+30^2+30^2+50^2+50^2+50^2+70^2+70^2+70^2+90^2+90^2+90^2=49200$

$\sum_{i=1}^n y^2_i =38^2+43^2+29^2+32^2+26^2+33^2+19^2+27^2+23^2+14^2+19^2+21^2=9540$

$\sum_{i=1}^n x_i y_i =30*38+30*43+30*29+50*32+50*26+50*33+70*19+70*27+70*23+90*14+90*19+90*21=17540$

With these we can find the sums:

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=49200-\frac{720^2}{12}=6000$

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}=17540-\frac{720*324}{12}{12}=-1900$

And the slope would be:

$m=-\frac{1900}{6000}=-0.317$

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

$\bar x= \frac{\sum x_i}{n}=\frac{720}{12}=60$

$\bar y= \frac{\sum y_i}{n}=\frac{324}{12}=27$

And we can find the intercept using this:

$b=\bar y -m \bar x=27-(-0.317*60)=46.02$

So the line would be given by:

$y=-0.317 x +46.02$

b) Plot the points and graph the line as a check on your calculations.

For this case we can use excel and we got the figure attached as the result.

c) Calculate S^2

In oder to calculate S^2 we need to calculate the MSE, or the mean square error. And is given by this formula:

$MSE=\frac{SSE}{df_{E}}$

The degred of freedom for the error are given by:

$df_{E}=n-2=12-2=10$

We can calculate:

$S_{y}=\sum_{i=1}^n y^2_i -\frac{(\sum_{i=1}^n y_i)^2}{n}=9540-\frac{324^2}{12}=792$

And now we can calculate the sum of squares for the regression given by:

$SSR=\frac{S^2_{xy}}{S_{xx}}=\frac{(-1900)^2}{6000}=601.67$

We have that SST= SSR+SSE, and then SSE=SST-SSR= 792-601.67=190.33[/tex]

So then :

$S^2=\hat \sigma^2=MSE=\frac{190.33}{10}=19.03$

5 0

3 years ago

A snail moved 375 centimeters in 5 hours. How fast was the snail moving? Solve for speed.

ivann1987 [24]

Answer: 75 cm per hour

Step-by-step explanation:

375 divided by 5=75

8 0

3 years ago

Read 2 more answers

The Brutus Gourmet Company produces delicious organic dog treats for canines with discriminating tastes. Management wants the bo

KiRa [710]

Answer:

Average range(R-bar) = Sum of the sample range for each sample/number of samples = (9+8+1+8+7) /5 = 33/5 = 6.6

Sample size = 8

For a sample size of 8 the factors for control limit for range (D3) = 0.136 (obtained from table of constraints for x-bar and R chart

LCL = R-bar × D3 = 6.6 × 0.136 = 0.90

Step-by-step explanation:

3 0

4 years ago

If f(x)=x+4 and g(x)=x^3 what is (g*f)(-3)

Molodets [167]

Step-by-step explanation:

g*f(x)=g(x+4)=(x+4)³

g*f(-3)=(-3+4)³

= 1³=1

4 0

3 years ago

1, 3,4,5,11, answer is 65 _ + (_-_)^2 +_x_

Y_Kistochka [10]

Answer:

1 + (11-4)^2 +3x5

Step-by-step explanation:

1 + (11-4)^2 +3x5

1 + (7)^2 + 3 x 5

1 + 49 + 15

50 + 15 = 65

5 0

3 years ago