Probability questions regarding Standard Normal distribution...

silentrevelation said:

X is a normal random variable , mean 11, variance 14.

First thing I did was...

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silentrevelation said:

Hi, I have a few prob&statistcs questions due for assignment and I was wondering if someone knowledgeable on the subject could look over my answers and tell me if I'm right or wrong. I'm using R (hopefully someone is familiar with the program) to answer these questions.

X is a normal random variable , mean 11, variance 14.

First thing I did was to take the square root of the variance to get the standard deviation, which is 3.741657.

P(X < 0)

I did pnorm(0,11.0,3.741657) and got 0.001641729 as an answer.

P(|X-10| < 2)

I did pnorm(12,11.0,3.741657)-pnorm(8,11.0,3.741657) and got 0.394027 as an answer.

70th percentile of X - 2 = 10.96213

For this question I subtracted 2 from the mean and did qnorm(.70,9,3.741657) and got 10.96213 as an answer.

Are my answers correct or incorrect? Can anyone help me out?

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stapel said:

All you've posted is a statement of values. What was the actual question? What are you supposed to be doing with these values?

Thank you!

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Suppose X is a normal random variable with a mean of 11 and a variance of 14. Using R calculate the following:

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