Download Probability Rules! (7.1)

September 20, 2012
Probability Rules!!
Event: a collection of possible outcomes
from some chance process.
Example: What are all of the possible
outcomes from tossing a coin three times?
HHH
HHT
HTH
THH
TTH
THT
HTT
TTT
The probability of any event is a number
between _____ and _____
All possible outcome together must have a
probability equal to _____
The probability that an event does not occur
is _________________________________
September 20, 2012
If two events have no outcomes in common,
the probability that one or the other occurs is
the sum of their individual probabilities.
P(A) + P(B) = P(C)
Example: Tossing a coin three times...
Let event A = getting 2 heads and 1 tail
Let event B = getting 3 heads
What's the probability of getting more heads than tails?
Answer: 1
2
Why is this true??
September 20, 2012
If all outcomes in the sample are equally
likely, the probability that event A occurs
can be found by:
number of outcomes corresponding to event A
P(A) = ___________________________
total number of outcomes in sample space
September 20, 2012
Activity 7.2
The Monte Hall Problem - Let's Make a Deal!!