Probability Help: Formulas for Random Variables with Mean 5 and Variance 12

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The discussion focuses on the application of formulas for random variables, specifically for a random variable x with a mean of 5 and a variance of 12. The transformation of x into y, defined as y = 3 + 9x, allows for the calculation of the expected value of y, which is 32, and the variance of y, which is 729. The standard deviation of y is therefore 27. The question of whether y is normally distributed is contingent on the distribution of x, which is not specified.

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So I took probability last year, and for one of my classes we have an optional refresher worksheet, but I cannot remember how to deal with random variables :(

I don't need the answer -- just some guidance on what formulas to use please!

x is a random variable with mean 5 and variance 12.

y = 3 + 9x

a) what is the expected valued of y?

b) what is the variance and SD of y?

c) is y normally distributed?

thank you so much!
 
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Welcome to PF, xhallie! :smile:

Here's a page I just googled, which I believe answers your questions:
http://www.kaspercpa.com/statisticalreview.htm
 

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