Question

A game involves drawing a single card from a standard deck. One receives 60 cents for an ace, 30 cents for a king, and 5 cents for a red card that is neither an ace nor a king. If the cost of each draw is 10 cents, what is the expected value?

Answer 1

The expected game value is -1 cent

Explanation:

Here, we want to calculate the expected value of the game

We have 4 aces and 4 kings, including 26 red cards

The number of aces is 4

Probability of drawing an ace is 4/52 = 1/13

Probability of drawing a king is also 4/52 = 1/13

There are 26 red cards

The number of red cards that are neither ace nor king

There are 2 red aces and 2 red kings

So the number of cards that are red but are not

aces nor kings are 26-2-2 = 22

The probability of selecting this is 22/52 = 11/26

So the expected value is simply the probability multiplied by the amount

Thus, we have;

(60 * 1/13) + (30 * 1/13) + (5 * 11/26)

= 60/13 + 30/13 + 55/26

= (120 + 60 + 55)/26 = 9.038 cents which is approximately 9 cents

we subtract this from the 10 cents we are playing with, thus we are left with 9-10 = -1 cent