Probability is a measure of the chance that something will happen. It is a measure of certainty or uncertainty
Let A be an event in a finitte sample space S. If each outcome in S is equally likely , then the probability that A occurs, denoted P(A), is given by
The probability of event A is the number of ways event A can occur divided by the total number of possible outcomes
Example:
A glass jar contains 7 red, 5 green, 9 blue and 3 yellow marbles. If a single marble is chosen at random from the jar, what is the probability of choosing a red marble?
solution:
the number of possible outcomes is in this case 7+5+9+3 =24
and A=red marble. There are 7 red marbles.
So, p(A)= p(A) is 7/24
Now is your turn.
what is the probability of choosing a green marble?
what is the probability of choosing a blue marble?
what is the probability of choosinga yellow marble?
what did you notice in your results? could a probability be bigger than one? explain why
Explore in your candy pacage M&M the probability of getting a yellow piece, a red piece and a green piece
A interesting problem solved using probability is to determine the blood type of a patient. Explore this example here.
References
Senk S. et al. (1998) Functions, Statistics and Trigonometry. The University of Chicago School Mathematics Project. Scott Foresman Addison Wesley.
Tversky, A., & Kahneman, D. (1982). Causal schemas in judgments under uncertainty. In D. Kahneman, P. Slovic, & A. Tversky (Eds.), Judgment under uncertainty: Heuristics and biases (pp. 117-128). Cambridge, UK: Cambridge University Press.
Franklin C. et al (2005) . A Curriculum Framework for PreK-12 Statistics Education. ASA
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