Since you've helped me with error in measurement I'll try and help you with financial expectation.
It looks long and hard but if you work in sections it's quite simple. What you do is you have a fraction of the event occuring and then you times that by the amount you win/lose..then you add the next fraction of the other event occuring and then times that by the amount you win/lose and keep doing this until the event's over.(Note, it's one long calculation and just key the numbers in one after the after, also if you're keying in the amount you're about to lose make sure you put the negative symbol in) I'll give you an example as my explanation isn't probably good enough, the example is straight from the text book.
->A game is played where a die is rolled. if a one or a six is rolled, the player wins $2 and if any other number is rolled the plaer loses $1. What is the financial expectation of this game? The calculation should look like this, it's long but you can work out the sections?
1/6 x 2 + 1/6 x -1 +1/6 x -1 + 1/6 x -1 + 1/6 x -1 +1/6 x 2
This should equal 0, which means that the financial expectation is $0
I truly hope I've helped both you and other people and good luck in Tuesdays exam!!