Math Is Fun Forum

Rom jeb

Guest

Normal Distribution Problem?

I have a Standard Deviation of 20.41 for one group and 19.357 for the other, but i have a mean of 38.5 for the former and 52.3 for the latter.

would this matter, as it would go over the graph if i used the 3 S.D

or would i just have whatever could fit in (e.g. with the 52.3 mean i could fit in the standard deviation of 19.357 twice before it goes over the graph)

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: Normal Distribution Problem?

Sorry I don't understand what you want to do with your data?

Rom Jeb

Guest

Re: Normal Distribution Problem?

Its for a normal distribution curve in a histogram

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: Normal Distribution Problem?

I know but what do you want to do with the graphs? What does the question ask you to do?

Rom Jeb

Guest

Re: Normal Distribution Problem?

oh right.

its for a statistics project, and i am summarising data for exam results

and it the hypothesis is trying to prove wherever state (government funded) schools do worse compared to independent (privately funded) schools

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: Normal Distribution Problem?

Let X be the variable with E(X) = 52.3 and Sd(X) = 19.357. Let Y be the variable with E(Y) = 38.5 and Sd(Y) = 20.41

Then consider X-Y. Assuming X-Y follows a normal distribution, you can work out

and

Once you have both of them, solve

to find the probability that X is greater than Y.