THEORETICAL PROBABILITY

THEORETICAL PROBABILITY

Theoretical probability is used to find the probability of an event when all the outcomes are equally likely.

• Equally likely outcomes have the same probability.

• If each possible outcome of an experiment is equally likely, then the experiment is said to be fair. 

EXAMPLE

• Andy has 20 marbles in a bag. Of these, 9 are clear and 11 are blue. Find the probability of drawing a clear marble from the bag? Write your answer as a fraction, as a decimal, and as a percent.

• 9/20, 0.45, 45%

Poll

DO YOU KNOW HOW TO CHANGE FROM FRACTION TO DECIMAL AND PERCENT?

• YES

• NO

• I WOULD LIKE AN EXPLANATION

Multiple Choice

Jane has 20 marbles in a bag. Of these 8 are green.

Find the probability of drawing a green marble

from the bag? Write your answer as a fraction, as a decimal, and as a percent.

• 8/20, 0.8, 80%

• 8/20, 0.4, 40%

• 8. 8%

• 20/8, 2.5, 2.5%

Open Ended

There are 13 boys and 10 girls on the track team. The name of each of the team members is written on an index card. A card is drawn at random to choose a student to run a sprint and the card is replaced in the stack.

Find the theoretical probability of drawing a boy’s name.

Write the answer as a fraction.

correct answer

13/23

A teacher has written the name of each student on a piece of paper and placed the names in a box. She randomly draws a paper from the box to determine which student will present the answer to the problem of the day. 

• If there are 15 boys and 12 girls in the class, what is the theoretical probability that a girl’s name will be drawn?

Multiple Choice

P(girl's name)

• 12/15

• 12/27

• 15/27

• 15/12

PROBLEM

You have 11 cards, each with one of the letters from the word mathematics.

Multiple Choice

Write your answer as a fraction, as a decimal to the nearest hundredth, and as a percent to the nearest whole percent.

FIND THE PROBABILITY OF DRAWING AN M FROM THE PLIE OF SHUFFLED CARDS.

• 2/11, 0.18, 18%

• 1/2, 50%, 0.5

• 1/11, 0.09, 9%

Multiple Choice

A number cube is rolled. Identify the probability of getting a number less than 4 as a fraction, as a decimal to the nearest hundredth, and as a percent to the nearest whole percent

• 1/3, 0.33, 30 %

• 1/3, 0.33, 33%

• 1/2, 0.5, 50%

• 1/2, 0.50, 20%

Multiple Choice

There are 40 balls in a bag. Of these 8 are white, 7 are blue, 12 are green, and 13 are yellow. Identify the probability of drawing a white ball as a fraction, as a decimal to the nearest hundredth, and as a percent to the nearest whole percent.

• 1/8, 0.13, 13%

• 1/5, 0.20, 20%

• 1/2, 0.50, 50%

• 1, 1, 100%