Find mean and standard deviation from histogram?

I think I know how to find the mean, half of cumulative frequency, but no idea how to find the standard deviation. It would be great if you could walk me through all steps and answers. Thanks!

yolohighup1 said:

I think I know how to find the mean, half of cumulative frequency, but no idea how to find the standard deviation. It would be great if you could walk me through all steps and answers. Thanks!

Click to expand...

There's a reason they instruct you to "approximate" the values, rather than finding "the" "exact" values: you're guessing, to a certain extent, from a picture!

My guess would be that they intend for you to note that the graph looks kind of like a normal curve, and then to use the 68-95-99.7 rule for normal curves. Can you find limits, approximately equidistant from your mean, which encompass rounds-about 68% of the data points? Then these limits tell you the approximate width of one standard deviation.