PreCalculus
40S Probability of Independent and Dependent Events II
December 14, 2011
　
Example 1: If the probability of not winning a game is 21/37, find the probability of wining the game.

P(Winning)=1-21/37=16/37
　
　
　
Example 2: A Kickoff consists of team A and B taking turns kicking 50 yard field goals. The first team to kick a field goal wins. Team A has a probability of 2/5 of scoring on any one shot and team B has a probability of 3/5 of scoring on any one shot.

a) If team B shoots first, what is the probability of team A winning on its first shot?

Team A

P(Ascore)=2/5

P(Amiss)=3/5 　

Team B

P(Bscore)=3/5

P(Bmiss)=2/5

P(Awin)= 2/5 * 2/5=4/25
　
　
　
b) If team A shoots first, what is the probability of team B winning on its second shot.
3/5*2/5*3/5*3/5
=54/625

Example 3: What is the probability of getting a sum of 3 on single throw of two dice.
Sample Space For Throwing Two Dice=36
1+2=3
2+1=3
　
P(Sum Of 3)=2/36=1/18
　
　
Example 4: What is the probability of getting a jack or a diamond on a single cut of a deck of 52 cards.

P(Jack)= 4/52

P(Diamond)= 13/52　　　　

P(JackDiamond)= 1/52

P(Jack or Diamond )= (4/52+13/52)-1/52

=17/52-1/52=16/52
　
　
　
　
　
　
　
　
　
　
　
　
　

Hey guys, this is Irish and today we learned about the “Probability of Independent and dependent events”.

Mutually Exclusive events are where events can not both occur at the same time. (The probability of drawing a king or a queen when a single card is drawn from a deck of cards – the card can not be king and queen at the same time).

• Probability for mutually exclusive events: P(E or F) = P(E) + P(F)
• Probability for non-mutually exclusive events: P(E or F) = P(E) + P(F) – P(E and F)
  

Complementary events are when one event occurs if and only if the other doesn’t.

• Complementary events: P(E) + P(F) = 1
  

Independent Events are when two events occur but do not influence the outcome of each other.

• Probability of Independent Events: P(E and F) = P(E) • P(F)
  

NOTE: DON’T REDUCE UNLESS OTHERWISE STATED

Example #1: Two cards are drawn from a desk of 52 cards. Find the probability that they are both face cards if the first card is…

a) replaced?
PFACE CARD (#1) = 12/52
PFACE CARD (#2) = 12/52
PBOTH FACE CARD = 12/52 • 12/52 → 9/169


b) not replaced?
PFACE CARD (#1) = 12/52
PFACE CARD (#2) = 11/51
PBOTH FACE CARD = 12/52 • 11/51 → 11/221

Example #2: A box contains 5 chocolate candies, 3 cherry candies and 7 caramel candies…

a) if one candy is chosen, what is the probability it will be cherry or caramel?
PCHERRY = 3/15
PCARAMEL = 7/15
PCHERRY and CARAMEL = 3/15 + 7/15 → 10/15

b) if two candies are drawn what is the probability that both are chocolate or both cherry? (without replacement).

PCHOCOLATE (#1) = 5/15
PCHOCOLATE (#2) = 4/14
PBOTH CHOCOLATE = 5/15 • 4/14 → 20/210

PCHERRY (#1) = 3/15
PCHERRY (#2) = 2/14
PBOTH CHERRY = 3/15 • 2/14 → 6/210
PCHOCOLATE and CHERRY = 20/210 + 6/210 → 26/210

Sample Space

Hey everyone, so here's our lesson from 12/6/11.

So, what is a Sample Space.

Well it is the complete set of all possible outcomes and is also useful in quickly determining the number of a particular outcome in an experiment.
To represent a sample space, tree diagrams and ordered pairs are often used.

Basic Probability Formula: Used to identify the probability that specific events will occur
P(E)= Success .
Sample Space

Example 1: A coin is flipped 3 times, sketch the sample space using a tree diagram.

Example 2: Using example #1, find the probability of tossing two heads.

P(E)= Success .
Sample Space

P(2 Heads) = 3 .

8

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Permutations - part 1

Hey everybody, this is Irene, and our lesson on November 22nd was about Permutations.

The definition of "PERMUTATION" is a set of distinct objects in an arrangement of objects without any repetition in a specific order.

And to "PERMUTE" a set if objects means to rearrange them.

The formula we use for Permutation is:

nPr = n!

________

(n-r)!

Where:

n = total number of objects

r = number objects selected

Hint: n > r

( n; must always be positive.)

Ex #1: How many three letter "words" composed from the 26 letters in the alphabet are possible if . . .

a) NO repetitions are allowed?

Method 1; (can only use formula is NO repetitions are allowed)

n = 26; because you have 26 letters to choose from.
r = 3; because you're trying to make 3 letter words.

sol'n

Method 2: "dash method" (can apply in both no repetition and repetition situations)




B) Repetitions allowed:

SPECIAL NOTE:

(Understand)
Homework: Permutations, Combinations & Binomial Theorem Assignment

due TOMORROW!

Factoral Notation

COUNTING PRINCIPLES:

This unit is all about counting… without actually counting.

FUNDAMENTAL COUNTING PRINCIPLE

If something can be chosen, or can happen, or be done, in m different ways, and, after that has happened, something else can be chosen in n different ways, then the number of ways of choosing both of them is m · n.

MULTIPLICATION PRINCIPLE:

ü When two events are dependent we multiply their results to find the total number of ways it occurs.

Key Words: “AND”, “BOTH”

ADDITIVE PRINCIPLE:

ü When two events are independent we add their results to find the total number of ways it occurs.

Key Words: “OR”, “EITHER”, “OPPOSITE”

EXAMPLE:

The executive of the Manitoba Association of Mathematics Teachers Association consists of three woman and two men. In how many ways can a president and a secretary can be chosen if:

1. The president is to be a female and the secretary male?

Using Dash Method:

3 and 2 6

President Secretary

2. The president is to be a male and the secretary female?

2 and 3 6

President Secretary

3. The president and secretary are to be of the opposite sex?

6 and 6 12

President Secretary

FACTORIAL NOTATION:

The symbol n! ( read as n factorial) means to multiply all of the positive integers from n consecutively down to 1

The factorial function (symbol: !) just means to multiply a series of descending natural numbers. Examples:

• 4! = 4 × 3 × 2 × 1 = 24
• 7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5,040
• 1! = 1

*n! = n(n-1)(n-2)…(3)(2)(1) , where n is an element of + integer.

EXAMPLE:

ü 24!(n+1)!

22!(n-1)!

ü 24 •23•22!(n+1)(n+0)(n-1)!

22!(n-1)!

ü 552 (n+1)(n+0)

1

ü 552(n+1)n