# Thread: Getting a new distribution for X(bar)

1. ## Getting a new distribution for X(bar)

Let X(bar) be the mean of a random sample of size 12 from the uniform distribution on the interval (0,1).
Approximate P(1/2 < X(bar) < 2/3).

No idea how to do this whatsoever.
I know you can use the moment generating function but I can't simplify it to make it work.
And sorry I can't overscore? on here, so X(bar) is sample mean.

Also, a general idea of how to approach these problems would be helpful too, I have other similar practice problems.

Any help would be greatly appreciated.

2. The sum of uniforms is not a uniform so I had expected a central limit problem here.
But with n=12 that's not really appropriate.
you can multiply by 12 and then figure out

$P\left(6<\sum_{i=1}^{12} X_i<8\right)$

which is a 12 fold integral with density 1.

3. Originally Posted by matheagle
The sum of uniforms is not a uniform so I had expected a central limit problem here.
But with n=12 that's not really appropriate.
you can multiply by 12 and then figure out

$P\left(6<\sum_{i=1}^{12} X_i<8\right)$

which is a 12 fold integral with density 1.
That makes sense, thanks for the help!

4. BUt it still is a pain in the..........