Assume the random variable X is normally distributed with u=50 and standard deviation o=7. compute the probability.

P(X34)=?

please explain how to get the answer.

Question

Assume the random variable X is normally distributed with u=50 and standard deviation o=7. compute the probability.

P(X>34)=?

please explain how to get the answer.

phi · Answer

This is hard to explain here. See http://www.khanacademy.org/math/probability/statistics-inferential/normal_distribution/v/ck12-org-normal-distribution-problems--z-score to get the main idea.

phi · Answer

to do your problem we need to first find the z-score.
the video explains that part.

anonymous · Answer

well from what i got from the video i think i do $$\frac{ 34-50 }{ 7 } = \frac{ -16 }{ 7 } = -2.29$$

phi · Answer

yes.  now we need to change that into a probability.  I am looking at his videos trying to find the one that explains how to do it.

anonymous · Answer

well using this for - z scores i got 0.011011

phi · Answer

yes, so you know this part!    you get about 1.1% chance or 0.011

anonymous · Answer

lol yah & thx!

anonymous · Answer

what answer do i put? i put 0.0110 but it says i'm wrong

anonymous · Answer

oh!! i think i got it

phi · Answer

oops, I wasn't thinking.

we found the area under the curve from -infinity up to 34.  in other words we found Pr(x≤34)
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