Bell curve

Hi,

I've made the bell curve graph from the file attached. Can someone guide me whether I have to include 2 new columns like 1 standard dev and 2
standard dev. How do I check for 68% observations within 1 standard deviation and 95% within 2 standard deviation range.

Why do you need to include 2 new columns?

To check for 68% of observations being within 1 standard deviation, you can use this formula:

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If you do it you'll see that the result is 63% (I suppose it's acceptable but it's up to you to decide). I'm sure you can figure out the rest.