Multiplication Rules of Probability

Will you use addition or multiplication for the following probability problem?

P(A and B)

• Addtion

• Multiplication

Five cards are drawn from a deck without replacement. Find the probabilities that all are red cards.

• (13/52)*(13/52)*(13/52)*(13/52)*(13/52)

• (13/52)*(12/51)*(11/50)*(10/49)*(9/48)

• (26/52)*(25/51)*(24/50)*(23/49)*(22/48)

• (26/52)*(26/52)*(26/52)*(26/52)*(26/52)

At a gathering consisting of 10 men and 20 women, two door prizes are awarded. Find the probability that both prizes are won by women.

• (20/30)*(19/30)

• (20/30)*(19/29)

• (20/20)*(19/20)

• (10/30)*(9/29)

Sixty-nine percent of household play computer games. Choose 4 heads of households at random. Find the probability that none play computer games.

• 0.69*0.69*0.69*0.69

• 0.69*0.68*0.67*0.66

• 0.31*0.31*0.31*0.31

• 0.31*0.30*0.29*0.28

What is the Multiplication Rule?

• P(A) ⋅ P(B|A)

• P(A) - P(B)

• P(A) ⋅ P(B)

• P(A) + P(B) - P(A ∩ B)

What is the Multiplication Rule?

P(A ∩ B) = ​ (a)  

• P(A) ⋅ P(B|A)

• P(A) - P(B)

• P(A) ⋅ P(B)

• P(A) + P(B) - P(A ∩ B)

To find the probability of 2 INDEPENDENT events, you ...

• Find the probability of event #1

• Find the probability of event #2

• Add the probability of both event #1 & event #2

• Multiply the probability of both event #1 & event #2

Given P(A) = .8 and P( B| A) = .3, find P( A and B).

• 2.6

• .12

• .24

• .38

What rule would I use to find the probability of event A and event B happening?

• Addition Rule

• Subtraction Rule

• Multiplication Rule

• Complement Rule

Probability of 2 dependent events

• P(A and B) = P(A) * P(B|A)

• P(A or B) = P(A) + P(B)

• P(A and B) = P(A) * P(B)

• P(A or B) = P(A) + P(B) - P(A ∩ B)