Probability

Probability measures how likely something is to happen, on a scale from 0 (impossible) to 1 (certain). It's calculated as the number of favourable outcomes divided by the total number of possible outcomes. When two things happen together — like flipping a coin AND rolling a die — you can list every combination to work out the chances.

Key terms

Favourable outcome:

An outcome that counts as a "success" for what you're measuring.

Total outcomes:

Every possible result that could happen.

Combined event:

Two or more things happening together, like a coin flip and a dice roll.

Questions

1. 1. How many possible outcomes are there when flipping a coin?

   • 1
   • 2
   • 3
   • 4

2. 2. The probability of an impossible event is:

   • 0
   • 0.5
   • 1
   • 2

3. 3. The probability of a certain event is:

   • 0
   • 0.5
   • 1
   • 2

4. 4. A bag has 1 red ball and 1 blue ball. The probability of picking red is:

   • 0
   • 1/4
   • 1/2
   • 1

5. 5. A standard die has how many faces?

   • 4
   • 6
   • 8
   • 10

6. 6. Probability is always a number between:

   • 0 and 1
   • 1 and 10
   • −1 and 1
   • 0 and 100

7. 7. A spinner has 4 equal sections, one of which is green. The probability of landing on green is:

   • 1/4
   • 1/3
   • 1/2
   • 1

8. 8. The probability of flipping a coin and getting heads is:

   • 0
   • 1/4
   • 1/2
   • 1

9. 9. Rolling a standard die, the probability of rolling a 6 is:

   • 1/6
   • 1/2
   • 1
   • 6

10. 10. An event that is certain has a probability of:

    • 0
    • 0.5
    • 1
    • 2

11. 11. An event that is impossible has a probability of:

    • 0
    • 0.5
    • 1
    • -1

12. 12. A bag has 3 red and 2 blue marbles. The probability of picking blue is:

    • 1/5
    • 2/5
    • 3/5
    • 1/2

13. 13. A spinner has 8 equal sections, 2 of which are red. The probability of landing on red is:

    • 1/8
    • 1/4
    • 1/2
    • 2/3

14. 14. A die is rolled. The probability of rolling an even number is:

    • 1/6
    • 1/3
    • 1/2
    • 2/3

15. 15. You flip a coin and roll a die at the same time. How many total possible combinations are there?

    • 6
    • 8
    • 10
    • 12

16. 16. Flipping a coin and rolling a die, what is the probability of getting Heads AND a 6?

    • 1/2
    • 1/6
    • 1/12
    • 1/18

17. 17. You have a red or blue shirt, and black or brown pants. How many different outfits can you make?

    • 2
    • 3
    • 4
    • 6

18. 18. Two coins are flipped. The probability of getting both Heads is:

    • 1/2
    • 1/3
    • 1/4
    • 1/8

19. 19. A café offers 3 types of coffee and 2 sizes. How many different orders (type + size) are possible?

    • 3
    • 5
    • 6
    • 9

20. 20. You roll a die and flip a coin. What is the probability of rolling an even number AND getting Tails?

    • 1/4
    • 1/3
    • 1/2
    • 1/12

21. 21. A restaurant has 2 starters and 4 mains. How many different starter+main combinations are there?

    • 4
    • 6
    • 8
    • 10