Free Grade 3 Probability Scale in Context Essentials Lessons
Free Grade 3 lessons for Probability Scale in Context Essentials: 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
Core
25 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- UnderstandExplain probability scale in context essentials
Explain probability scale in context essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate probability scale in context essentials
Calculate probability scale in context essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare probability scale in context essentials
Compare probability scale in context essentials accurately in a familiar context.
Assessed by: Exit ticket of four short items
- EvaluateJustify probability scale in context essentials
Justify probability scale in context essentials 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 Probability Scale in Context Essentials 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 1 red, 8 blue and 3 green counters. One is picked at random. Find P(red).[1]
- 2.A bag has 1 red, 5 blue and 2 green counters. One is picked at random. Find P(red).[1]
- 3.A bag has 2 red, 8 blue and 3 green counters. One is picked at random. Find P(red).[1]
- 4.A bag has 2 red, 2 blue and 2 green counters. One is picked at random. Find P(red).[1]
- 5.A bag has 4 red, 2 blue and 1 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 6.A bag has 7 red, 7 blue and 4 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 7.A bag has 6 red, 2 blue and 0 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 8.A bag has 2 red, 1 blue and 5 green counters. One is picked at random. Find P(red) and P(not red).[2]
- 9.A bag has 3 red and 8 blue counters. Two are picked with replacement. Find P(both red).[3]
- 10.A bag has 3 red and 2 blue counters. Two are picked with replacement. Find P(both red).[3]
- 11.A bag has 2 red and 6 blue counters. Two are picked with replacement. Find P(both red).[3]
- 12.A bag has 2 red and 5 blue counters. Two are picked with replacement. Find P(both red).[3]
Show answers and working
1. P(red) = 1/12
Total counters = 12. P(red) = 1/12 = 1/12.
2. P(red) = 1/8
Total counters = 8. P(red) = 1/8 = 1/8.
3. P(red) = 2/13
Total counters = 13. P(red) = 2/13 = 2/13.
4. P(red) = 1/3
Total counters = 6. P(red) = 2/6 = 1/3.
5. P(red) = 4/7, P(not red) = 3/7
Total counters = 7. P(red) = 4/7 = 4/7. P(not red) = 1 − 4/7 = 3/7.
6. P(red) = 7/18, P(not red) = 11/18
Total counters = 18. P(red) = 7/18 = 7/18. P(not red) = 1 − 7/18 = 11/18.
7. P(red) = 3/4, P(not red) = 1/4
Total counters = 8. P(red) = 6/8 = 3/4. P(not red) = 1 − 3/4 = 1/4.
8. P(red) = 1/4, P(not red) = 3/4
Total counters = 8. P(red) = 2/8 = 1/4. P(not red) = 1 − 1/4 = 3/4.
9. 9/121
P(red) = 3/11 each time. Independent, so multiply: 3/11 × 3/11 = 9/121.
10. 9/25
P(red) = 3/5 each time. Independent, so multiply: 3/5 × 3/5 = 9/25.
11. 1/16
P(red) = 2/8 each time. Independent, so multiply: 2/8 × 2/8 = 1/16.
12. 4/49
P(red) = 2/7 each time. Independent, so multiply: 2/7 × 2/7 = 4/49.
Worked examples
A bag has 5 red, 5 blue and 2 green counters. One is picked at random. Find P(red).
- Total counters = 12.
- P(red) = 5/12 = 5/12.
- Answer: P(red) = 5/12
A bag has 5 red, 2 blue and 4 green counters. One is picked at random. Find P(red) and P(not red).
- Total counters = 11.
- P(red) = 5/11 = 5/11.
- P(not red) = 1 − 5/11 = 6/11.
- Answer: P(red) = 5/11, P(not red) = 6/11
A bag has 4 red and 7 blue counters. Two are picked with replacement. Find P(both red).
- P(red) = 4/11 each time.
- Independent, so multiply: 4/11 × 4/11 = 16/121.
- Answer: 16/121
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 Probability Scale in Context Essentials lesson really free?
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- What should a learner already know before this?
- Start with Working with Probability Scale. Each one has its own free lesson, worksheet and quiz.
- How is the lesson 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 Probability Scale in Context Essentials?
- Move on to Probability Scale in Context Techniques, Probability Scale in Context Word Problems, Probability Scale in Context Common Errors, Introducing Probability Scale, which build directly on this idea.
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