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aliina [53]
3 years ago
7

25 scores from all of the students who took the test. She sees that the mean score is 134 with a standard deviation of 6.0547. T

he superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 13. Is there evidence that the standard deviation of test scores has decreas
Mathematics
1 answer:
Tomtit [17]3 years ago
7 0

Answer:

WE fail to reject the Null and conclude that ; Standard deviation of test hasn't decreased.

Step-by-step explanation:

The hypothesis :

H0 : σ = 13

H1 : σ < 13

Using the Chisquare Square statistic :

χ² = (n-1)*s²/σ²

Sample size, n = 25

s² = 6.0547²

σ² = 13²

χ² = (25 - 1)*6.0547² / 13²

χ² = 879.82541016 / 169

χ² = 5.206

The degree of freedom, df = 25 - 1 = 24

The Pvalue(5.206, 24) = 0.99981

Reject H0, if Pvalue < α ;

Since Pvalue > α ; WE fail to reject the Null and conclude that ; Standard deviation of test hasn't decreased.

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EMERGENCY (NEED HEP NOW!!!)
diamong [38]

Answer:

x=-2.25,y=-2.25

Step-by-step explanation:

The given system is

4x - y =  - 9 \\ 3x - 3y = 0

We want to solve the system for x and y that makes the system true.

Let us multiply the first equation by 3 while maintaining the second equation:

12x -3 y =  - 27 \\ 3x - 3y = 0

Subtract the current second equation from the first one.

12x =  - 27

Divide through by 12:

x =  -  \frac{27}{12}  =  - 2.25

From the second equation we have:

3x = 3y

This implies that:

x = y =  - 2.25

8 0
3 years ago
PLEASEEEE help <br> i know i am saying this again
BartSMP [9]

Answer: for the first it is not direct varition while for the second one it i s

Step-by-step explanation:

6 0
1 year ago
Thank you very much for your help!
Kobotan [32]
For a.
x^2+y^2=25

For b.
(x-4)^2+(y-3)^2=25

For c.
(x-5)^2+(y-4)^2=9


Hope that helps
5 0
3 years ago
I need help for this to pass my last math class please help and show your work
Maksim231197 [3]
-12 + 3x + 2 = 5x - 10 - 8x 
-10 + 3x = -3x -10
-10 + 6x = -10
6x = 0 
x = 0 
3 0
3 years ago
There were 340,000 cattle placed on feed. Write an equivalent ratio that could be used to find how many of these cattle were bet
monitta
We see this same problem pop up here on Brainly every
couple of months.  Nobody yet has ever given us enough
information to answer it. 

There's no information here that we can use to find out the
weight of any of the cattle placed on feed.  There must be
some more information BEFORE this. 

Maybe it's in the previous question in the book or on the
homework sheet, and nobody who posts this question ever
includes the information from the question before it.
3 0
3 years ago
Read 2 more answers
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