Question

Using the 68-95-99.7% rule find the Standard deviation from this graph.

Answer 1

Do you know what standard deviation is?

Answer 2

Standard deviation, \(\Large \color{red}{σ}\), is how spread out the numbers are.
In a standard world, \(\Large σ=1 \)

Look at your graph, by what measurement are they spread out by?

Answer 3

Do you just estimate the percentage increase as in 2 ish% increase? Not sure how that would transfer over to the x axis.

I understand the rule I'm just have troubling applying it to the graph.

Answer 4

And they are spred out by intervals of +5 marks.

Answer 5

in what interval is 99% of the values between?

Answer 6

100% of the values, which is close to 99.7%, are between 30 and 90.
68, 95, 99.7 cover 3 positive and 3 negative standard deviations
can you answer it now?

Answer 7

So you just split it into half. So 3 standard deviations split equally from the mean is around about 10?

Answer 8

each

Answer 9

If I chose 10 how would I verify it?

Answer 10

there are 3 standard deviations to the right of the center (the mean)
and 3 standard deviations to the left of the center.
that gives you 6 standard deviations
divide the range by that

Answer 11

the range of the variable is (90 - 30) = 60

Answer 12

60 / 6 st. dev 's = 10

Answer 13

do you see in this picture how 6 standard deviations cover
99.7 of the values , which is basically 100% of the values
http://www.statisticshowto.com/wp-content/uploads/2013/09/standard-normal-distribution.jpg

Answer 14

thanks so much