Probability

• Maybe it's just the way I came to it, but I think probability is the key concept in statistics.
• It's also an easy place to start.
• If I flip a coin, how likely is it to come up heads?
• If I flip it 5 times, how likely is it to come up heads each time?
• In a deck of cards, if I pick two, how likely is it to be a pair?
• How likely are you to win the lottery?
• Let's assume numbers between 1 and 40, and you pick 6.
• First how likely are you to pick one on your first try? 6/40
• Assuming that's been removed, how many on the second try? 5/39
• So, for all 6 you get (6*5*4*3*2*1)/40*39*38*37*36*35.
• 720/2.76*10^9 = 2.60527*10^-7 = 0.0000000260527=2.6 in 10 million.
• I used excel for these numbers. It works pretty well for a lot of simple stats.