In a game, a man wins rupees five for a six and loses rupee one for any other number, when a fair die is thrown. The man decided to throw a die thrice but to quit as and when he gets a six. Find the expected value of the amount he wins/loses.

Explanation

`P(5)=1/6`

`P(-1)=5/6`

Expected value=`sumPX=[5P_5+4P_4+3P_3-3P_3]`

`5*1/6+(4*5)/(6*6)+(3*5*5)/(6*6*6)+(5*5*5(-3))/(6*6*6)`

=0.