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Kitty [74]
3 years ago
6

A test has a mean of 80 with a standard deviation of 4. Which of the following scores is within one standard deviation of the me

an?
A
75
B
77
С
BO
D
90
E
09
Mathematics
1 answer:
Bogdan [553]3 years ago
7 0

Answer:

B

Step-by-step explanation:

Mathematically, we shall be using the z-score here

Z-score = (x-mean)/SD

From the question, mean = 80 and SD = 4

So we want to get the option in the question that has a z-score of 1 or below

Let’s look at 75

80-75 = 5 ( this is clearly above 1 standard deviation of 4)

For 77;

80 -77 = 3

This is less than the standard deviation of 4, meaning it is within 1 standard deviation of the mean

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A researcher surveyed 150 high school students and found that 68% played a musical insturment. What would be a reasonable range
maria [59]

Answer:

The reasonable range for the population mean is (61%, 75%).

Step-by-step explanation:

The interval estimate of a population parameter is an interval of values that consist of the values within which the true value of the parameter lies with a certain probability.

The mean of the sampling distribution of sample proportion is, \hat p.

One of the best interval estimate of population proportion is the 95% confidence interval for proportion,

CI=\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p(1-\hat p)}{n}}

Given:

n = 150

\hat p = 0.68

The critical value of <em>z</em> for 95% confidence level is:

z_{\alpha/2}=z_{0.05/2}=z_{0.025}=1.96

Compute the 95% confidence interval for proportion as follows:

CI=\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p(1-\hat p)}{n}}

     =0.68\pm1.96\sqrt{\frac{0.68(1-0.68)}{150}}\\\\=0.68\pm 0.0747\\\\=(0.6053, 0.7547)\\\\\approx (0.61, 0.75)

Thus, the reasonable range for the population mean is (61%, 75%).

5 0
4 years ago
From 16 to 0 percent decrease
11Alexandr11 [23.1K]
Decrease just means getting less. 

Decreased way: 
16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1 

Hope this helped :D


4 0
3 years ago
What is the name of the line of reflection for the pair of figures?
Bas_tet [7]

The line of reflection that maps one shape into the other is line m.

<h3>What is the name of the line of reflection for the pair of figures?</h3>

The line of reflection is the line that maps one heart into the other heart. Such that the line must lie exactly between the two shapes, and divide the plane into two equal images.

By looking at the given image, we can see that the line of reflection that maps one heart into the other is the line M.

If you want to learn more about reflections:

brainly.com/question/4289712

#SPJ1

8 0
2 years ago
Precalculus please help
JulijaS [17]

Answer:

amplitude = 2

period = 4

midline = y = -1

equation = either 2sin(\frac{pi}{2}x+\frac{pi}{2}  )-1 or 2sin(\frac{pi}{2}(x+1) )-1 depending on what format you're using

Step-by-step explanation:

the amplitude is the distance from the bottommost point to the topmost point

so if we use the points (0,1) and (2,-3), the min y value is -3 and the max y value is 1

so amplitude = ymax - ymin = 1 - - 3 = 4

amplitude = 4

the period is the distance it takes to complete one cycle

we have (0,1) and (4,1) which are two crest points

the distance between these is x2 - x1 = 4 - 0 = 4

period = 4

the midline is a horizontal line bisecting the sin line, which would be in the middle of its min and max y values

we already found that ymax = 1 and ymin = -3

so the midline would be y = (ymax + ymin) / 2 = (1 -3) /2 = -1

midline = y = -1

to find the sin equation, we will fill out the equation

asin(b(x-d))+c

a is the amplitude = 2

b = 2π/period = 2π/4 = π/2

c is the vertical shift. the midline of sine is originally at y = 0

since it is at y = -1 here, the vertical shift is -1 - 0 = -1

d is the horizontal shift. the middle of the upwards portion of the sine graph is originally at x = 0, but in the picture we see that it is at x = -1 so the shift is -1 - 0 = -1

a = 2, b = π/2, c = -1, d = -1

plug these values into the equation to get

asin(b(x-d))+c

2sin(π/2(x--1))+-1

=2sin(π/2(x+1))-1

=2sin(πx/2+π/2)-1

equation = either 2sin(\frac{pi}{2}x+\frac{pi}{2}  )-1 or 2sin(\frac{pi}{2}(x+1) )-1 depending on what format you're using

4 0
3 years ago
One number is 4 less than a second number. twice the second number is 19 less than 5 times the first. find the two numbers.
o-na [289]
The answer is because i know so
4 0
3 years ago
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