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sladkih [1.3K]
3 years ago
11

One hundred teachers attended a seminar on mathematical problem solving. The attitudes of representative sample of 12 of the tea

chers were measured before and after the seminar. A positive number for change in attitude indicates that a teacher's attitude toward math became more positive. The twelve change scores are as follows. 4; 7; −1; 1; 0; 5; −3; 2; −1; 6; 5; −2(a) What is the mean change score?
(b) What is the standard deviation for this population?
(c) What is the median change score?
(d) Find the change score that is 2.2 standard deviations below the mean.
Mathematics
1 answer:
zzz [600]3 years ago
3 0

Answer:

a) 1.9

b) 3.25

c) 1.5

d) -5.25

Step-by-step explanation:

We are given the following in the data:

4, 7, -1, 1, 0, 5, -3, 2, -1, 6, 5, -2

a) Mean change score

Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}

Mean =\displaystyle\frac{23}{12} = 1.9

b)  standard deviation for this population

\text{Standard Deviation} = \sqrt{\displaystyle\frac{\sum (x_i -\bar{x})^2}{n-1}}  

where x_i are data points, \bar{x} is the mean and n is the number of observations.

Sum of differences = 126.92

S.D = \sqrt{\dfrac{126.92}{12}} = 3.25

c) median change score

Sorted data: -3, -2, -1, -1, 0, 1, 2, 4, 5, 5, 6, 7

Median:\\\text{If n is odd, then}\\\\Median = \displaystyle\frac{n+1}{2}th ~term \\\\\text{If n is even, then}\\\\Median = \displaystyle\frac{\frac{n}{2}th~term + (\frac{n}{2}+1)th~term}{2}

\text{Median} = \dfrac{6^{th}+7^{th}}{2} = \dfrac{1+2}{2} = 1.5

d) change score that is 2.2 standard deviations below the mean.

\mu - 2.2(\sigma)\\1.92 - 2.2(3.25) = -5.25

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3 years ago
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lidiya [134]

Answer:

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6 0
2 years ago
Dada la ecuacion 25x2 + 4y2 = 100, determina las coordenadas de los vertices, focos, las longitudes de los respectivos ejes mayo
Likurg_2 [28]

Answer:

The given equation is

25x^{2} +4y^{2}=100

Which represents an elipse.

To find its elements, we need to divide the equation by 100

\frac{25x^{2} +4y^{2} }{100} =\frac{100}{100} \\\frac{x^{2} }{4} +\frac{y^{2} }{25} =1

Where a^{2} =25 and b^{2}=4. Remember that the greatest denominator is a, and the least is b. So, we extract the square root on each equation.

a=5 and b=2.

In a elipse, we have a major axis and a minor axis. In this case, the major axis is vertical and the minor axis is horizontal, that means this is a vertical elipse.

The length of the major axis is 2a=2(5)=10.

The length of the minor axis is 2b=2(2)=4.

The vertices are (0,5);(0,-5) and (2,0);(-2,0).

Now, the main parameters of an elipse are related by

a^{2}=b^{2} +c^{2}, which we are gonna use to find c, the parameter of the focus.

c=\sqrt{a^{2}-b^{2} }=\sqrt{25-4}=\sqrt{21}

So, the coordinates of each focus are (0,\sqrt{21}) and (0,-\sqrt{21})

The eccentricity of a elipse is defined

e=\frac{c}{a}=\frac{\sqrt{21} }{5}  \approx 0.92

The latus rectum is defined

L=\frac{2b^{2} }{a}=\frac{2(4)}{5} =\frac{8}{5} \approx 1.6

Finally, the graph of the elipse is attached.

7 0
3 years ago
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Inessa [10]
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3 years ago
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Hi can someone help me out. This is due by the end of the day.​
solmaris [256]

Answer:

b. Divided

Step-by-step explanation:

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3 years ago
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