probability3 work.notebook
Do Now: Check HW answers and take out calculators. Ask questions!!!
Pg 691
Probability with Two Outcomes
Bernoulli Experiment ­ trials are independent and each trial has only two outcomes: success and failure.
If probability of success is p and the probability of failure is 1 ­ p = q, then the probability of r successes in n independent trials is:
nCr p
r
qn­r
This is called the binomial probability formula.
probability3 work.notebook
Example: A waiter knows from experience that 7 out of 10 people who dine alone leave a tip. Tuesday evening, the waiter served 12 lone diners.
What is the probability, to the nearest thousandth, that the waiter received a tip from 9 of these diners?
2) What is the probability that 2 shows on three of the dice when four dice are tossed?
probability3 work.notebook
3) A company that makes breakfast cereal puts a coupon for a free box of cereal in 3 out of every 20 boxes. What is the probability that Mrs. Sullivan will find 2 coupons in the next 5 boxes of cereal that she buys?
4) A fair die is tossed 5 times. What is the probability of tossing a 6:
a) exactly once
b) exactly twice
c) exactly 3 times
d) exactly 4 times
e) exactly 5 times
f) zero times
probability3 work.notebook
5) Jack's batting average is .2. What is the probability that he will get one hit in the next three times at bat?
At Least and At Most Probability
Using the binomial theorem to find the probability of something like getting 8 heads when tossing a coin 10 times:
The answer is: 10C8 (.5)8(.5)2
But what if the question was:
P(at least 8 heads)=P(8H)+P(9H)+P(10H)
probability3 work.notebook
So what would the probability be of
P(at most 4 heads)= ?
See pg 701
probability3 work.notebook
probability3 work.notebook
3)
probability3 work.notebook
Homework: pg 699­700 # 3 ­ 11 odd
pg 706 # 3 ­ 13 odd, 19