Probability Simplified

Probability: Simplified

You can do it!

Probability is a 7th grade topic, but this is very simplified so you can get a head start. Besides, you are smart kids!

Probability is not negative, and is never more than 1 (Decimal/ fraction scale), never more than 100%, and is never an improper fraction.

What Probability ISN'T:

Probability can be represented as a decimal (0-1), a percent (0%-100%), or a simplified fraction.

What can it be shown as?

Probability is the chance of an event happening.

Multiple Choice

What can probability be?

• All of the Below/Above

• Decimal

• Fraction

• Percent

Likelihood

What is likelihood?

Likelihood is basically probability on a 0-1 scale, except in words. These are the most common ways these words are used:

0: Impossible (Is not possible to happen) 1: Certain (Without a doubt will happen) 0.5: Not more likely or unlikely (half way, may or may not) Between 0.1-0.4: Unlikely (Probably Not) Between 0.6 and 0.9: Likely (Probably)

Multiple Choice

What is the probability that you are sleeping as you answer this question?

• 0; Impossible

• 0.5; Maybe or Maybe not

• 1; Certain

Poll

How do you feel about probability so far?

• This is pretty easy to understand, I get it.

• I might need a little extra help.

Open Ended

Summarize probability in a sentence so far.

Probability Formula: Fractions

To find the probability in fraction form, take your total amount as the denominator and the favorable amount as the numerator. For example, what is the probability that you pull a yellow marble out of a bag, randomly, when there are 7 yellows, 2 blues, and 1 red? Well, the total is 10, and you want one of 7 yellows, so the probability would be 7/10. Normally, you would simplify, but you can't with the example.

Lets try out some problems!

Multiple Choice

Mrs. Crumplebottom put the names of all of her students onto a fair wheel. What is the percent chance that a student is chosen and their name starts with H? Simplify.

• 5/21

• 5/22

• 4/20

• 0.8

Well, if you didn't, how'd you go wrong? Here, you would just count the number of students, which is 22, then count the number of students with the letter H at the beginning, which is 5. ​

​Did you get that right?

Multiple Choice

A thief is on a block with 16 houses. He decides that he is going to steal from 8 of them, randomly. What is the probability a house gets stolen from that street? Simplify.

• 1/2

• 1/16

• 8/16

• 8/71

Multiple Choice

The new doctor in training has to give a patient one of the 5 different red-colored shots. While looking away, he forgot which one he was supposed to use, and they were UN-labeled. What is the probability he took the wrong shot? Simplify.

• 4/5

• 1/5

• 3/5

• 2/5

• 1