Monday, February 25, 2008

Scribe Post : Probability

Hey guys.. ok so today we worked more on probability specifically theoretical and experimental probability. As a recap:

Experimental Probability is the chance of something happening based on completing an experiment.
Ex: Tossing 3 pennies, using heads to represent boys and tails for girls, then repeating the toss 10 times, representing a family with three children.

Theorectical Probability is the chance of something happening based on realistic circumstances.
Ex.When having a child, there are only two outcomes. Either the child is a girl or boy, therefore there is a 50% chance it will be a girl and 50% chance it will be a boy. For the second child, there are no restrictions as to wether the child will be a girl or boy, so then once again the chance of having a girl remains 50% and for a boy 50% aswell.

Today we learned that we can easily use a tree diagram to help us find outcomes. For example using the example as stated under the theorectical definition:

Remember: inorder for it to be easily followed or understandable, the diagram must be expressed neatly.

So if you follow the branches of the tree diagram, you would get outcomes such as:




B G G - exactly 2 girls outcome #1


G B G - exactly 2 girls outcome #2

G G B - exactly 2 girls outcome #3


For this example, it asks how many outcomes consist of exactly 2 girls. The answer would be "3 out of 8"

Today we learned how to calculate probability on our TI-83 which we would call stimulating binomial experiments (number of trials, probability of success, number of stimulations). So using the example: In a family of three children, what is the probability that 2 of the children will be girls? We calculated it in class.

So on your TI-83 follow step by step intructions:
1. select [MATH]
2. slide over to [PROB]
3. select [randBin] (random binomial experiment)
4. type in (1, 3/8,40)
- 1 represents the outcome for success.
- 3/8 represents the theorectical probability of success
- 40 represents the # of times the experiement is repeated
5. click [ENTER]
- this will calculate the outcome
- "1" representing successes and "0" representing failures.
Instead of counting the number of time the experiment is successful, it can be calculated throught the calculator, so with #5 of the the steps above still on your screen continue the following:
6. select [STO] [2nd] [L1]
- this will store the information in List 1 (L1)
7. select [2nd] [STAT]
8. select [MATH] slide down to [sum] [2nd] [L1]
- this will calculate of the successes or all the failures.

Like Mr. K said in class informfation such as the information we entered into the calculator: (1, 3/8, 40) you will need to know how to calculate for yourself for test, quizzes and the exam.

ok well think that is it. See ya later!
The Scribe for tomorrow will be Melissa S.

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