Question

An american roulette wheel has 38 slots, of which 18 are red, 18 are black, and 2 are green (0 and 00). if you spin the wheel 38 times,
a.intuitively, how many times would you expect the ball to wind up in a green slot?
b.use the formula for expected value to verify your intuition.

Answer 1

Intuitively, one would think the ball would land in the green spot 2 out of the 38 times, since there are 38 slots and 2 are green.

The probability that it lands in a green section is 2/38.  Multiplying this by the number of times the experiment is performed, we get (2/38)(38) = 2.