Virginia SOL Math / Grade 4 / Probability & Statistics

4.PS.2

Probability of Simple Events

What you'll learn

  • Model the probability of a simple event
  • Describe outcomes as certain, likely, unlikely, equally likely, or impossible
  • Write the probability of a simple event as a fraction

Words to know

Probability —
how likely an event is to happen
Outcome —
one possible result
Certain —
sure to happen
Impossible —
cannot happen
Equally likely —
outcomes with the same chance

Why it matters Probability helps us judge chance, from a coin flip in a game to the likelihood of rain.

Worked examples

Model ItI do

A bag has 3 red and 2 blue marbles. What is the probability of drawing red?

There are 3 red marbles out of 5 marbles in all. Probability is favorable outcomes over total outcomes, so P(red) = 3/5.

Try It TogetherWe do

You spin a spinner with 4 equal parts, all green. How likely is green?

Every part is green, so green must come up. That makes spinning green a certain event, with probability 4/4 = 1.

Now YouYou do

A number cube is labeled 1 to 6. What is the probability of rolling a 3?

Count how many faces show a 3 out of all 6 faces, and write it as a fraction. Check your answer in the back.

Practice

Mastered 0 of 11

Warm-up

Ease in with the basics.

  1. 1.A coin is flipped. What is the probability of heads?

  2. 2.A bag has only red tiles. Drawing red is what kind of event?

  3. 3.What is the probability of rolling a 7 on a 1-to-6 number cube?

On Level

The core Quick Check from the book.

  1. 1.A bag has 4 red and 4 blue marbles. Is drawing red likely, unlikely, or equally likely?

  2. 2.What is the probability of rolling a 7 on a 1-to-6 number cube?

  3. 3.A coin is flipped. What is the probability of heads?

  4. 4.A bag has only yellow tiles. Drawing yellow is what kind of event?

  5. 5.A bag has 1 green and 5 red marbles. What is the probability of green?

Challenge

Stretch your thinking.

  1. 1.A bag has 2 red, 3 blue, and 5 green marbles. What is the probability of drawing green?

  2. 2.A spinner has 8 equal parts: 3 red, 4 yellow, and 1 blue. What is the probability of landing on red?

  3. 3.On a 1-to-6 number cube, what is the probability of rolling an even number?