Post on 20-Jan-2016
Conditional Probability: the likelihood that an event will occur GIVEN that another event has already occurred.
A two way table & tree diagrams can represent these types of events.
The probability of event B given event A has occurred is represented as P(B|A)
Example: P(18 to 24|female) = 5668/9321 ≈ 0.6081
1) What is the probability that a student chosen at random would be 35 years or older?
2) What is the probability that a student chosen at random would be 35 years or older given that they are female?
The intersection of events (events happening together) can be found as follows:
P(A and B ) or P(A ∩ B) = P(A) * P(B|A)
What if you want to determine if two variable events are independent of each
other?Is age
independent of gender?
If P(B) = P(B|A), then the events are independent.
Are online chat rooms dominated by the young adults? Of all adult users...
29% are 18-29 years (A1) 47% are 30 – 49 years (A2)
24% are 50+ years (A3) 47% of the 18-29 years use chat rooms
21% of the 30-49 years use chat rooms 7% of the 50+ years use chat rooms
What percent of adult chat
room users are 18 – 29
years old?
Weekly Practice
Pg 417 #33, 36 Pg 423 #37, 38
Pg 425 #44 Pg 430 #46, 48, 50
Pg 446 # 72 – 74
Pg. 453 # 86
Pg 455 #94