Given $\displaystyle u = 12$ $\displaystyle o = 3$ , what is the probability of P(X<9) ?

I have no clue how to do it...

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- Jan 26th 2009, 06:02 AMFaisal2007Mini prob. question
Given $\displaystyle u = 12$ $\displaystyle o = 3$ , what is the probability of P(X<9) ?

I have no clue how to do it... - Jan 26th 2009, 06:05 AMgalactus
Am I to assume that u is $\displaystyle {\mu}$ for the mean and

o is $\displaystyle {\sigma}$ for the standard deviation?.

If so, $\displaystyle z=\frac{x-{\mu}}{\sigma}$

$\displaystyle z=\frac{x-12}{3}$

If x=9, then z=-1.

What is the z score for -1?. - Jan 26th 2009, 06:08 AMFaisal2007
Is it 0.15?

Why did you find the z score though ? - Jan 26th 2009, 10:54 AMmr fantastic
- Jan 27th 2009, 04:29 AMFaisal2007
- Jan 27th 2009, 11:18 AMmr fantastic
Surely you're told the distribution! What is the context of the question? Is it a question from a problem set on normal distribution? Binomial distribution ....?

If you can't provide all the necessary background information to the question you're not going to get much help.