I DO KNOW MR.PITT HAS ALREADY DONE A PROBABILITY PAGE!

Probability is demonstrated with a fraction, for example:
There are 10 marbles in a bag, 5 are black, 2 are white, 1 is each blue and red.
What is the probability of picking a black marble at random?
Answer: Obviously
Now a harder question:

What is the probability of choosing a black marble, putting it back, then choosing a red?

Answer: You would do , which makes

Even Harder:

What is the probability of choosing a black without putting it back, and then choosing a blue?

A tree diagram of a coin being tossed 3 times looks like this:

image: tree diagram and probabilities

The probability of three heads is:
P (H H H) = 1/2 × 1/2 × 1/2 = 1/8
P (2 Heads and a Tail) = P (H H T) + P (H T H) + P (T H H)
= 1/2 × 1/2 × 1/2 + 1/2 × 1/2 × 1/2 + 1/2 × 1/2 × 1/2
= 1/8 + 1/8 + 1/8
= 3/8
Question:

image: tree diagram with missing probabilities

Fill in the missing probabilites

Answer:

image: tree diagram with probabilities

Ed Walden 8J
Feel free to add or change anything if you think (or is) wrong

Probability is demonstrated with a fraction, for example:

There are 10 marbles in a bag, 5 are black, 2 are white, 1 is each blue and red.

What is the probability of picking a black marble at random?

Answer: Obviously

Now a harder question:

What is the probability of choosing a black marble, putting it back, then choosing a red?

Answer: You would do , which makes

Even Harder:

What is the probability of choosing a black without putting it back, and then choosing a blue?

Answer: Do

Tree Diagrams:

FIRSTDownload this PowerPoint Presentation!

A tree diagram of a coin being tossed 3 times looks like this:

The probability of three heads is:

P (H H H) = 1/2 × 1/2 × 1/2

=1/8P (2 Heads and a Tail) = P (H H T) + P (H T H) + P (T H H)

= 1/2 × 1/2 × 1/2

+1/2 × 1/2 × 1/2+1/2 × 1/2 × 1/2= 1/8

+1/8+1/8= 3/8

Question:

Fill in the missing probabilites

Answer:

Ed Walden 8J

Feel free to add or change anything if you think (or is) wrong

Still don't get it? Ask Mr. Pitt!