Distribution problem! Help!

Question

1.  The probability distribution of a random variable X is given.

x	1	2	3	4
P(X = x)	0.3	0.1	0.4	0.2

Compute the mean, variance, and standard deviation of X. (Round your answers to two decimal places.)

mean
variance
standard deviation

Answer 1

mean (mu) = sum x(i) * P(x(i)) for i = 1 to 4

variance = [sum x(i)^2 * P(x(i))] - mu**2

standard deviation = square root (variance)