1. Basic Probability Fact Rules
Statistics and Risk Management
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Not Always Simple
Sometimes groups need to be combined.
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Additive Rule
100 M&Ms in a Bag
24 Blue & 16 Red ones.
p(b or g)= =.40
You have a .40 probability of randomly drawing out a Blue or Red one.
Add the example where you know the number of students for all four class levels, but you want to determine the probability of randomly selecting a student for a study out of combined Freshmen-Sophomore class.
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Not Always Simple
Sometimes you will have several times or tries.
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Multiplicative Rule
100 M&Ms in a Bag
24 Blue ones.
p(b,b)=.24x.24=.056
You have a .056 probability of randomly drawing out 2 Blue ones in a row.
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Problems
Flip a Coin Once
Probability it will be heads.
Flip a Coin Twice
Probability it will be heads twice.
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Problems
Roll a Pair of Dice.
Probability: it will be a pair of sixes.
p(s)=???????
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