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Lubov Fominskaja [6]
3 years ago
10

How to find standard deviation from percentile for normal distribution?

Mathematics
1 answer:
QveST [7]3 years ago
8 0
The standard deviation of what?  Percentiles from any normal distribution look the same, just like the unit normal, so you can't really determine the standard deviation of the original scores. You can determine a z score from a percentile.  That tells us the number of standard deviations, positive or negative, a given score is away from the mean score.  It's a normalized test result.

Your percentile is (a hundred times) the probability that another score is less than your score.  We have a normal distribution, so that probability is the integral of the standard normal from negative infinity to our normalized score.  

Let's call the percentile rank p, already scaled between zero and 1.

p=.5 corresponds to a z score z=0 because the fiftieth percentile means we got an exactly average score, 0 standard deviations away from the mean.

We know 68% of the probability will be between -1 and +1 standard deviation.  So z=-1 corresponds to p=.5-.68/2=.16 and
z=1 corresponds to p=.5+.68/2=.84

Similarly, 95% of the probability will be between -2 and +2 standard deviations.  So z=-2 corresponds to p=.5-.95/2=.025 and
z=2 corresponds to p=.5+.95/2=.975

That's about the list I can do off the top of my head. I think three standard deviations is 99.7%. For the rest we just consult a z table or integrated normal table.  We find p in the body of the table (maybe |.5-p| depending on the table) and then the column headings tell us our z score.

In this modern age, your computer can do this for you quickly

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Answer:

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Step-by-step explanation:

is it 794.561 × 10(2)?

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Answer:

The answer to your question is in the picture below

Step-by-step explanation:

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3 years ago
Write 4/5x3/8 in lowest term
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2 years ago
​ b(1)=−7 b(n)=b(n−1)+12 ​ Find the 4th term in the sequence
forsale [732]

4th term = 29

to generate the terms, substitute n = 2, 3, 4 into the rule

noting that b(1) = - 7

b(2) = b(2 - 1) + 12 = b(1) + 12 = -7 + 12 = 5

b(3) = b(3 - 1) + 12 = b(2) + 12 = 5 + 12 = 17

b(4) = b(4 - 1) + 12 = b(3) + 12 = 17 + 12 = 29




8 0
3 years ago
Read 2 more answers
PLEASE HELP! WILL GIVE BRAINLIEST!
irinina [24]

Answer:

1: y intercept = 5

2: y interpcept = -2

3: y intercept = -3

Step-by-step explanation:

So for the 1st and 3rd ones (the graphs), all you have to do is find which y matches the x value of 0

The 2nd one is a bit harder. I’ll explain it the best I can

So in the y section, you see that -4 goes to -3 when the x is raised by 1. There for everytime the x raises by 1, so does the y. That means when x = 0, the y = -2

3 0
2 years ago
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