Free Grade 3 Working with Conditional Probability Worksheets
Free Grade 3 worksheets for Working with Conditional Probability: 12 real questions with a full answer key and worked solutions. Probability measures how likely something is, from 0 (impossible) to 1 (certain). P(event) = favourable outcomes ÷ total outcomes. For independent events, multiply.
Free
Higher
15 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- RememberIdentify working with conditional probability
Identify working with conditional probability accurately in a familiar context.
Assessed by: Exit ticket of four short items
- UnderstandExplain working with conditional probability
Explain working with conditional probability accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate working with conditional probability
Calculate working with conditional probability accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare working with conditional probability
Compare working with conditional probability accurately in a familiar context.
Assessed by: Exit ticket of four short items
Prerequisites
Close these gaps first — each has its own free lesson, worksheet and quiz.
How Working with Conditional Probability works
Probability measures how likely something is, from 0 (impossible) to 1 (certain). P(event) = favourable outcomes ÷ total outcomes. For independent events, multiply.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.A bag has 4 red, 6 blue and 5 green counters. One is picked at random. Find P(red).[1]
- 2.A bag has 3 red, 8 blue and 1 green counters. One is picked at random. Find P(red).[1]
- 3.A bag has 8 red, 1 blue and 2 green counters. One is picked at random. Find P(red).[1]
- 4.A bag has 7 red, 2 blue and 2 green counters. One is picked at random. Find P(red).[1]
- 5.A bag has 8 red, 6 blue and 5 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 6.A bag has 3 red, 7 blue and 0 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 7.A bag has 5 red, 2 blue and 5 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 8.A bag has 8 red, 5 blue and 1 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 9.A bag has 1 red and 1 blue counters. Two are picked with replacement. Find P(both red).[3]
- 10.A bag has 1 red and 6 blue counters. Two are picked with replacement. Find P(both red).[3]
- 11.A bag has 6 red and 2 blue counters. Two are picked with replacement. Find P(both red).[3]
- 12.A bag has 2 red and 3 blue counters. Two are picked with replacement. Find P(both red).[3]
Show answers and working
1. P(red) = 4/15
Total counters = 15. P(red) = 4/15 = 4/15.
2. P(red) = 1/4
Total counters = 12. P(red) = 3/12 = 1/4.
3. P(red) = 8/11
Total counters = 11. P(red) = 8/11 = 8/11.
4. P(red) = 7/11
Total counters = 11. P(red) = 7/11 = 7/11.
5. P(red) = 8/19, P(not red) = 11/19
Total counters = 19. P(red) = 8/19 = 8/19. P(not red) = 1 − 8/19 = 11/19.
6. P(red) = 3/10, P(not red) = 7/10
Total counters = 10. P(red) = 3/10 = 3/10. P(not red) = 1 − 3/10 = 7/10.
7. P(red) = 5/12, P(not red) = 7/12
Total counters = 12. P(red) = 5/12 = 5/12. P(not red) = 1 − 5/12 = 7/12.
8. P(red) = 4/7, P(not red) = 3/7
Total counters = 14. P(red) = 8/14 = 4/7. P(not red) = 1 − 4/7 = 3/7.
9. 1/4
P(red) = 1/2 each time. Independent, so multiply: 1/2 × 1/2 = 1/4.
10. 1/49
P(red) = 1/7 each time. Independent, so multiply: 1/7 × 1/7 = 1/49.
11. 9/16
P(red) = 6/8 each time. Independent, so multiply: 6/8 × 6/8 = 9/16.
12. 4/25
P(red) = 2/5 each time. Independent, so multiply: 2/5 × 2/5 = 4/25.
Worked examples
A bag has 8 red, 3 blue and 4 green counters. One is picked at random. Find P(red).
- Total counters = 15.
- P(red) = 8/15 = 8/15.
- Answer: P(red) = 8/15
A bag has 1 red, 1 blue and 1 green counters. One is picked at random. Find P(red) and P(not red).
- Total counters = 3.
- P(red) = 1/3 = 1/3.
- P(not red) = 1 − 1/3 = 2/3.
- Answer: P(red) = 1/3, P(not red) = 2/3
A bag has 7 red and 7 blue counters. Two are picked with replacement. Find P(both red).
- P(red) = 7/14 each time.
- Independent, so multiply: 7/14 × 7/14 = 1/4.
- Answer: 1/4
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Writes probability as a ratio like 3:5.
Correction: Use a fraction, decimal or percentage.
Adds probabilities for 'and' events.
Correction: 'And' means multiply when events are independent.
Teacher tips
- · Run real experiments with dice and compare to theory.
Parent tips
- · Talk about the chance of rain from the forecast.
Real-life applications
- · Weather forecasts, games, insurance.
Assessment objectives
How mastery is evidenced, and which standards it maps to.
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Frequently asked
- Is this Grade 3 Working with Conditional Probability worksheet really free?
- Yes. Every worksheets on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Introducing Conditional Probability, Venn Diagrams. Each one has its own free lesson, worksheet and quiz.
- How is the worksheet sequenced?
- Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
- What comes next after Working with Conditional Probability?
- Move on to Conditional Probability in Context, Sample Space Diagrams, Tree Diagrams, Venn Diagrams, which build directly on this idea.
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