statistics and probability

Question

betting on the color red in the game of roulette has 18/38 chance of winning. what is the expected value and variance for the number of wins in a series of 50 bets on red?

Answer 1

E(x) = np = 50*18/38 = 900/38 = 450/19 

var(x) = npq = 50*18/38*20/38 = 4500/361