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vladimir2022 [97]
3 years ago
7

A random sample of 25 statistics examinations was selected. The average score in the sample was 76 with a variance of 144. Assum

ing the scores are normally distributed, the 99% confidence interval for the population average examination score is _____.
Mathematics
1 answer:
Mazyrski [523]3 years ago
6 0

Answer:

99% confidence interval for the population average examination score is between a lower limit of 69.2872 and an upper limit of 82.7128.

Step-by-step explanation:

Confidence interval = mean +/- margin of error (E)

mean = 76

variance = 144

sd = sqrt(variance) = sqrt(144) = 12

n = 25

degree of freedom (df) = n - 1 = 25 - 1 = 24

confidence level (C) = 99% = 0.99

significance level = 1 - C = 1 - 0.99 = 0.01 = 1%

t-value corresponding to 24 df and 1% significance level is 2.797

E = t×sd/√n = 2.797×12/√25 = 6.7128

Lower limit = mean - E = 76 - 6.7128 = 69.2872

Upper limit = mean + E = 76 + 6.7128 = 82.7128

99% confidence interval is (69.2872, 82.7128)

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The table shows the values of a function f(x).
QveST [7]

Answer:

The average rate of change is =-4

Step-by-step explanation:

The average rate of change from x=a to x=b of f(x) is given by;

=\frac{f(b)-f(a)}{b-a}

We want to find the average rate of change of the function represented in the table  from x=-2 to x=2.

=\frac{f(2)-f(-2)}{2--2}

From the table f(-2)=25 and f(2)=9

The average rate of change from x=-2 to x=2 is

=\frac{9-25}{2--2}

=\frac{-16}{4}

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3 0
3 years ago
Simplify 5^2•(4+2^3)
Marta_Voda [28]

Remember to follow PEMDAS, and left -> right rule.

First, solve the Parenthesis:

(4 + 2^3)

Solve the exponent.

2^3 = 2 x 2 x 2 = 4 x 2 = 8

4 + 8 = 12

_______________________________________________________________

(5^2) x (12)

5^2 = 5 x 5 = 25

25 x 12

_______________________________________________________________

Multiply

25 x 12 = 300

________________________________________________________________

300 is your answer

________________________________________________________________

<em>~Rise Above the Ordinary</em>

3 0
2 years ago
Part 3: Write the equation of and graph an ellipse.
tensa zangetsu [6.8K]

Answer:

Step-by-step explanation:

The center is halfway between vertices, at (4, -6).

It is also halfway between foci.

:::::

The vertices are vertically aligned, so the parabola is vertical.

General equation for a vertical ellipse:

 (y-k)²/a² + (x-h)²/b² = 1

with

 center (h,k)

 vertices (h,k±a)

 co-vertices (h±b,k)

 foci (h,k±c), c² = a²-b²

Apply your data and solve for h, k, a, and b.

center (h,k) = (4, -6)

h = 4

k = -6

vertices (4,-6±a) = (4,-6±9)

a = 9

foci (4,-6±c) = (4,-6±5√2)

b² = a² - c² = 9² - (5√2)² = 31

b = √31

The equation becomes

 (y+6)²/81 + (x-4)²/31 = 1

:::::

length of major axis = 2a = 18

length of minor axis = 2b = 2√31

8 0
2 years ago
Solve each question using the quadratic formula? X2+4x+3=0
Sergeeva-Olga [200]
<span>x=<span>−<span><span>1<span> or </span></span>x</span></span></span>=<span>−<span>3 i think lol</span></span>
8 0
3 years ago
The Wonderful Widget Company's earnings have declined to the point where they need to reduce the number of employees from 1500 1
AleksandrR [38]

Answer:6%

Step-by-step explanation:

Decrease = 1500 - 1410= 90

% decrease = (90/1500)*100%

= 6%

7 0
3 years ago
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