What is the expected value to gain in following game and how much one is expected to win if one plays 100100 games?

In a card game return on getting an ace, other than club, is $5$5 but if it is a club he gets extra $10$10 and getting a club, other than ace, gets you $1$1.

1 Answer
Jan 10, 2017

He is expected to win $0.81$0.81 per game and

in 100100 games, he is expected to win $80.77$80.77

Explanation:

When we have to find expected win or loss, what we have to do is identify probability of the event pp and multiply it with expected return rr.

If more than one events are there, which are mutually exclusive and their probabilities are p_1,p_2,p_3,---p1,p2,p3, and corresponding returns are r_1,r_2,r_3,---r1,r2,r3, and aggregate expectation is sum(p_ir_i)(piri).

and if their are nn trials wins are nxxsum(p_ir_i)n×(piri)

Coming to the problem,

probability of getting an ace, other than club, is 3/52352 and return on it is $5$5

probability of getting a club, other than ace, is 12/521252 and return on it is $1$1

probability of getting ace of club is 15/521552 and return on it is $15$15, (here as he is expected to win $5$5 for an ace and extra $10$10 for club, he wins $15$15. If it is, however, $1$1 for a club and extra $10$10 for an ace, he wins $11$11).

So for one game (considering $15$15 for ace of club), one wins

(3/52xx5+12/52xx1+1/52xx15)(352×5+1252×1+152×15)

= (15+12+15)/52=$42/52=$0.8115+12+1552=$4252=$0.81

and in 100100 games, it is 100xx42/52=$80.77100×4252=$80.77

Considering $11$11 for ace of club, one wins

(3/52xx5+12/52xx1+1/52xx11)(352×5+1252×1+152×11)

= (15+12+11)/52=$38/52=$0.7315+12+1152=$3852=$0.73

and in 100100 games, it is 100xx38/52=$73.08100×3852=$73.08