sample standard deviation of grouped data

[imalwrighty]

I figured the correct figures for the frequency, and f times x squared, but can't figure how to calculate the formula for sample standard deviation. I put it in the calculator exactly how it is written with all the the data plugged in, but the answer comes out wrong. I wonder if I am calculating wrong, or putting it in the calculator wrong.

 

[stapel]

Since you haven't posted any of the necessary information, we can't see what you're working with, what you've done, or what answers you got. As a result, I'm afraid there is no way to reply. Sorry.