If the casino decides to set the machine to have 3 apples appear
in a row once randomly in 121 plays on the machine, how much the
casino is expected to make ? 
The casino will win $0.21 for every 121 plays on the machine
ie
Expected value per 121 plays = $0.01 x 120 - $0.99 x 1= $0.21
or
Expected value per play = $0.01 x 120/121 - $0.99 x 1/121 =
$0.00174 (3sf)
What if the 3 apples appear on the 88th play and the player wins
the one dollar and stop playing, will the casino lose money
? 
The casino will not lose money as long as there are many players
who wish to play on the machine ie the next time the 3 apples will
appear once randomly in the next 154 plays.
Hence, a lot of psychology is used in designing the jackpot
machine to make the machine with lots of music, tones, visual
effects to keep the players entertained to play the machine.
This simple jackpot machine is very simple. It can be enhanced
by introducing more fruits, more rows and more ways of winning with
different payouts to make the game more exciting so that the
players will keep coming back to play the game.
The calculation of the expected value per play for the casino
will be
= $0.01 x k1 - w1k1 - w2k2 ......... - WnKn
