Grade 8 Probability & Data worksheet
from Gradelings · Name: ______________________
How to explain it
- Probability = favourable outcomes ÷ all possible outcomes.
- Mean: add and divide. Median: the middle. Mode: the most common.
- Use whichever measure best describes the data.
Example: Find the mean of 3, 5, 6 and 10. Add: 3 + 5 + 6 + 10 = 24. Divide by 4: 24 ÷ 4 = 6. Answer: 6
Question 1
A shop sells 3 kinds of shirts and 2 kinds of pants. How many different outfits can you make with one of each?
answer box
6
Hint: Multiply the choices: 3 × 2 = 6.
Question 2
A bag has 5 red, 4 blue and 3 green marbles. What is the probability of picking a blue marble? Type it as a fraction in lowest terms.
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1/3
Hint: P(blue) = favourable ÷ total = 4/12, which is 1/3 in lowest terms.
Question 3
A bag has 5 red, 4 blue and 3 green marbles. What is the probability of NOT picking blue? Type a fraction in lowest terms.
answer box
2/3
Hint: Not blue means red or green: 5 + 3 = 8 marbles out of 12. That is 2/3. (Or 1 − 4/12.)
Question 4
Sam spins a spinner 50 times and it lands on green 29 times. What is the experimental probability of green? Type a fraction in lowest terms.
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29/50
Hint: Experimental probability = successes ÷ trials = 29/50 = 29/50.
Question 5
A spinner lands on blue with probability 3/4. About how many blue spins do you expect in 12 spins?
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9
Hint: Expected number = probability × trials = 3/4 × 12 = 9.
Question 6
What is the mean of these numbers? 17, 20, 18, 15, 25
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19
Hint: Add them up: 17 + 20 + 18 + 15 + 25 = 95. Divide by 5: 95 ÷ 5 = 19.
Question 7
What is the median of 17, 11, 15, 5, 22?
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15
Hint: Put them in order: 5, 11, 15, 17, 22. The middle number is 15.
Question 8
A data set has one extremely large value (an outlier). Which measure changes the most because of it?
- the mean
- the number of values
- the median
- the mode
the mean
Hint: The mean uses every value, so one huge number pulls it up. The median only cares about the middle position.
Question 9
What is the mode of 10, 10, 18, 10, 6, 4?
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10
Hint: The mode is the value that appears most often. 10 appears 3 times.
Question 10
What is the range of 9, 12, 15, 25, 30?
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21
Hint: Range = greatest − least = 30 − 9 = 21.
Answer key
- 1. 6
- 2. 1/3
- 3. 2/3
- 4. 29/50
- 5. 9
- 6. 19
- 7. 15
- 8. the mean
- 9. 10
- 10. 21
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