Henry I. answered • 10/01/15
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By counting is the short answer.
Using a calculator, you have found that the mean is about 13.06 and the standard deviation 2.24. That means that the range of one standard deviation is from 13.06+2.24 to 13.06-2.24 or 15.3 to 10.8. You can simply count how many data points out of the total of 90 fall between these two lines.
The rule that governs normal curves (of which this is not one if you look at the histogram) is that 68% of the data will fall within one s of the mean. How close is this? Well, by my count, every value from 11 to 15 falls within our limits, so that would be 52 data points, which is 58% of all the data.
The same procedure is used for the 2 and 3 standard deviation questions, but for those, you would use + or - 2.24 (2).
Henry I.
There are 90 total data points (from the given frequency chart). We counted 52 of those 90 data points falling within one SD of the mean. 52 is 58% of 90. Hope this answers your question.
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07/18/19
Arnav S.
is there any way to get that by using a calculator? or do you have to do it manually.
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04/24/20
Henry I.
Arnav, if you're asking whether there's a way to calculate standard deviation without a calculator, yes, there is, but it's quite tedious. In most statistics classes, you learn how to do it by hand mainly so you can understand the underlying math. After that, you would only use a calculator. Here's a link to a good explanation: https://www.mathsisfun.com/data/standard-deviation-formulas.html
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04/24/20
Jimin I.
Hi, i wondering to know how did you find 58%07/18/19