I believe the answer given is wrong for the following question:

My answer is . The book says that . Who's right?Quote:

Determine the mean and standard deviation of the random variable whose probability distribution is

x = 2, P(x) = .1

x = 4, P(x) = .2

x = 6, P(x) = .4

x = 8, P(x) = .2

x = 10, P(x) = .1