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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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Suppose there is a pile of​ quarters, dimes, and pennies with a total value of ​​$1.08
WINSTONCH [101]

Answer:

a)

if 1 quarter = $ 0.25

  1 dime = $ 0.10

  1 penny = $ 0.01

so to make the total of $1.08 and its is also required to calculate the number of each coins present without being able to make change for a dollar

therefore we say;

1 Quarter + 8 dimes + 3 penny

: ( 1 × 0.25 ) + ( 8 × 0.10 ) + ( 3 × 0.01 )

: 0.25 + 0.80 + 0.03 = $ 1.08

b)

Now if you have a 4 Quarters, you have change for $1.

If you have 5 dimes, you have change for 2 Quarters.

If you have nickel; one of those can combine with 2 dimes to have a change for a Quarter.

If you have 5 pennies, you have enough change for 1 nickel

Therefore

(4-1)×0.25 + (5-1)×0.1 + (0×0.05) + (5-1)×0.01 = x

(3 × 0.25) + ( 4 × 0.1) + 0 + ( 4 × 0.01) = x

x = 0.75 + 0.4 + 0.04

x = $ 1.19

PROVED

6 0
3 years ago
Y=2x+1<br> How do I put this equation in order pair for a table
Ber [7]

Answer:

I think you would have to draw lines like is the graph book, you will see that they have two axes which is the y and the x.You will then have to fix in numbers and indicate the y= 2x+1.

Step-by-step explanation:

hope it helps

8 0
3 years ago
Solve the right triangle.<br> Round your answers to the nearest tenth.
Nadya [2.5K]

*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆*――*☆**☆*――*☆*――*☆*――*☆

Answer: c=38.89

b=29.79

<A=40

Explanation:

I hope this helped!

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5 0
3 years ago
Read 2 more answers
A plastic box has a length 4 cm longer than its width. The area of the rectangular top of the box is 77 square cm. Find the leng
finlep [7]

Answer: the length is 11 cm.

The width is 7 cm.

Step-by-step explanation:

Let L represent the length of the rectangular plastic box.

Let W represent the width of the rectangular plastic box.

The area of the rectangular top of the box is 77 square cm. This means that

LW = 77- - - - - - - ;- - - -1

The plastic box has a length 4 cm longer than its width. This means that

L = W + 4

Substituting L = W + 4 into equation 1, it becomes

(W + 4)W = 77

W² + 4W = 77

W² + 4W - 77 = 0

W² + 11W - 7W - 77 = 0

W(W + 11) - 7(W + 11) = 0

W - 7 = 0 or W + 11 = 0

W = 7 or W = - 11

Since the width cannot be negative, then W = 7cm

L = 77/7 = 11 cm

4 0
3 years ago
PLEASE HELP!!!!!!!!! Solve the system using elimination method.
NeX [460]

Answer:

The answer is (6,12)

107x= 642

x=6

7•6 +2y=66

y= 12

8 0
3 years ago
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