Theoretical probability

key notes:

The probability is the number of favorable outcomes out of the number of possible outcomes.

Learn with an example

📢 You pick a card at random.

What is P(less than 2)?

Write your answer as a percentage.

______ %

There are 4 cards, numbered 1, 2, 3 and 4. The only number less than 2 is 1. There is 1 number less than 2.

P(less than 2) = 1/4

Write your answer as a decimal. Then convert your answer to a percentage.

1/4 = 0.25 = 25%

P(less than 2) = 25%

📢 You flip a coin.

What is P(heads)?

Flipping a coin has two possibilities: heads or tails.

P(heads) = 1/2

📢 You spin the spinner once.

What is P(2)?

Write your answer as a percentage.

_________ %

The spinner has 4 equal sections, numbered 1, 2, 3 and 4.

P(2) = 1/4

Write your answer as a decimal. Then convert your answer to a percentage.

1/4 =  0.25 = 25%

P(2) = 25%

let’s practice!