Number Properties: Probability

Question 1

What is probability?

Answer 1

quantity that expresses the likelihood of an event.

Probability: Number of desired outcomes/Number of possible outcomes

Question 2

How do you calculate the probability of an event?

Answer 2

Calculate Numerator and denominator separately.

Denominator:

1. Use combinatorics formula
2. OR Manually count the number of outcomes

Numerator:
Manually count with chart or visualize it.

Question 3

How do you calculate the probability of more than one event when the question has AND between the two events?

Answer 3

You must calculate the probability of each event separately. Then since there is the AND, you would multiply those two probability factors to get the total probability.

Question 4

How do you calculate the probability of more than one event when the question says that only one of the multiple options can happen?

For example: weather report says 40% of sun, 25% chance of rain, and 35% chance of hail. What is the probability that it rains or hails today?

Answer 4

OR would mean that you add the two probabilities. So, 25% chance of rain plus 35% chance of hail = 60% chance of rain OR hail.

Question 5

How do you calculate “at least “ or “at most” probability problems?

Answer 5

Use 1- P(Not A). With not A being the inverse of what it is asking for.
For example, if we want the probability that Michele will pull out AT LEAST one marble, it is easier to calculate the probability where she would pull out NO red marbles.

Question 6

What should you use if the question asks for a probability of something to happen but the probability of it NOT happening is likely to be smaller?

Answer 6

Use 1- P(Not A). With not A being the inverse of what it is asking for.

Question 7

What is the anagram model and how do you use it?

Answer 7

It is a chart where you plot out each element and write Y or N depending on if the element fits in the pick

Use it to find the number of possible outcomes.

For example, finding the possible pairs from 5 things.

A, B, C, D, E
Y, Y, N, N, N

That would give you 5! /2!3! =10

Question 8

what is fundamental counting and when do you use it? PS 148 PS228 OG15

Answer 8

Use it for geo problems that asks “How many choices for each point” or in a diagram of a maze with multiple choices and paths.

Total choices = product of the number of options at each decision point.