In a game, a man wins Rs 5 for getting a number greater than 4 and loses Rs 1 otherwise, when a fair die is thrown, The man decided to throw a die thrice but to quit as and he gets a number greater than 4. Find the expected value of the amount he Wins/loses.
Let 'n' denote the number of throws required to get a number greater than 4 and X denotes the amount won/lost The man may get a number greater than 4 in the very first throw of the die or in second throw on is third throw.
Let p = probability of getting a number greater than 4
thus we have the following distribution for x.
Number of thrown (n) 1 2 3 3
Amount lost(x) 5 4 3 -3
Probability(p(x))
is the expected amount he could win