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April 24, 2014

April 24, 2014

Posted by **Jessica** on Wednesday, November 14, 2012 at 5:57pm.

A hwy engineer knows that his crew can lay 5 miles of hwy on a clear day, 2 miles on a rainy day, and only 1 mile on a snowy day. Suppose that the probabilities are as follows:

Outcome prob/random variable: clear .6/5, rain .3/2, snow .1/1

Find the mean (expected value) and the variance

Can anyone at least tell me where to start????

- Stats -
**RD Statistics**, Thursday, November 15, 2012 at 12:19amX P(X) x*P(X) x^2*P(X)

5 0.6 3 15

2 0.3 0.6 1.2

1 0.1 0.1 0.1

Mean = sum x*P(X)=3.7

sum (x^2 * P(X)) = 16.3

Variance = (x^2 * P(X)) - Mean^2

=16.3 - (3.7)^2 = 2.61

Mean = 3.7 miles and variance = 2.61 miles square

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