# A random sample of size 36 is selected...?

• Jan 30th 2010, 07:38 PM
Mitchell
A random sample of size 36 is selected...?
A random sample of size 36 is selected from a population whose mean is 60 and standard deviation is 6. Calculate the probabillity that:
59 ≤ X ≤ 61
• Jan 30th 2010, 11:00 PM
mr fantastic
Quote:

Originally Posted by Mitchell
A random sample of size 36 is selected from a population whose mean is 60 and standard deviation is 6. Calculate the probabillity that:
59 ≤ X ≤ 61

I assume X is the random variable 'mean of the sample'. Read this: Sampling distribution - Wikipedia, the free encyclopedia
• Jan 31st 2010, 09:14 AM
Mitchell
Yeah it is. I meant to put x-bar but it showed up as just X for some reason. But, I'm still not sure what I'm supposed to do here. Do I just find the standard error?
• Feb 1st 2010, 12:01 AM
mr fantastic
Quote:

Originally Posted by Mitchell
Yeah it is. I meant to put x-bar but it showed up as just X for some reason. But, I'm still not sure what I'm supposed to do here. Do I just find the standard error?

Did you read the link? What did it say about the distribution that $\overline{X}$ follows? Where are you still stuck?