Need help with normal distribution question?

College student2

I don’t understand what you’re supposed to do to get the mean and standard deviation here??

(edited 1 month ago)

Reply 1

Nitrotoluene

Original post by College student2

I don’t understand what you’re supposed to do to get the mean and standard deviation here??

Okay, so you've got a table with Mass, Midpoint, and Frequency, plus the mean (mu) and standard deviation (sigma) below.
To figure out the mean:

What does the midpoint tell you for each mass range?

What's the frequency for each?

Mix those two together to see how each range adds to the overall data. Once you know each interval's contribution, what do you need to find the average mass? Think about weighted averages.
For standard deviation: It's all about how spread out the data is. What's the first thing you need to know before calculating it? (Hint: You just figured it out above.)
Once you have the mean, how far is each midpoint from it? Why do we square that difference for standard deviation? How does the frequency of each interval affect things when you add up those squared differences? After adding the weighted squared differences, what's next to get the variance? Finally, how do you get the standard deviation from the variance?
Here is my 2 cents!
Ciao,
Sandro