HOMEWORK QUESTIONS?. 5.2 TWO-WAY TABLES PROBABILITY MODELS A probability model describes chance...
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Transcript of HOMEWORK QUESTIONS?. 5.2 TWO-WAY TABLES PROBABILITY MODELS A probability model describes chance...
PROBABILITY MODELS
A probability model describes chance behavior by listing the possible outcomes in the sample space and giving the probability that each outcome occurs.
Example:Color of Marble
Red Green Blue
Probability 0.4 0.1 0.5
ARE THESE MUTUALLY EXCLUSIVE?
• Turning left and turning right
• Drawing a king and drawing an ace
• Tossing a coin
• Drawing a king and drawing an ace
• Turning your head and scratching your foot
ADDITION RULE FOR MUTUALLY EXCLUSIVEIf A and B are mutually exclusive, P(A or
B) = P(A) + P(B)
For example, find the probability that you pull an ace or a king out of a deck of cards.
ANOTHER EXAMPLE
In a game of soccer, the probability of scoring no goals (event A) is 20%. The probability of scoring exactly 1 goal (event B) is 15%.
Find P(A and B)
Find P(A or B)
TWO-WAY TABLES
Students in a college statistics class wanted to find out how common it is for young adults to have their ears pierced. They recorded data on two variables – gender and whether the student had a pierced ear – for all 178 people in the class. Here is the two-way table describing their results.
Suppose we choose a student at random. Find the probability that the student:
a) has pierced ears
b) is a male with pierced ears
c) is a male or has pierced ears
Gender Yes No Total
Male 19 71 90
Female 84 4 88
Total 103 75 178
Define events!
A – is male
B – has pierced
ears
ONE MORE EXAMPLE
Let A be the event that the person is a female and B be the event that the person is underweight. Try to answer these on your own:
1.P(A) =
2.P(B) =
3.P(A or B) =
4.P(A and B) =