Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
Level 1 · Warm-up
1 This spinner has 5 equal sectors, 2 of them red. What is P(red) as a decimal?
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2/5 = 0.4.
2 Write these probabilities as decimals.
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1/2 = 0.5; 3/4 = 0.75.
3 P(A) = 0.35. What is P(not A)?
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1.00 − 0.35 = 0.65.
Level 2 · Core
4 A spinner has red, blue and green sections. P(red) = 0.5 and P(blue) = 0.3. What is P(green)?
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1 − (0.5 + 0.3) = 0.2.
5 P(blue) = 0.15, and red is twice as likely as blue. Find P(red) and P(blue or red).
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Red = 2 × 0.15 = 0.3. Together 0.15 + 0.3 = 0.45.
6 A bag has 10 counters, 3 of them red. What is P(red) as a decimal?
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3/10 = 0.3.
Level 3 · Challenge
7 A bag has 20 counters: 5 red, 4 blue and the rest green.1 P(red) = 0.25.
2 P(green) = 0.55.
3 P(blue) = 0.4.
Which statements are correct?
2 P(green) = 0.55.
3 P(blue) = 0.4.
Which statements are correct?
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5/20 = 0.25 (1 ✓). Green: 20 − 9 = 11, 11/20 = 0.55 (2 ✓). Blue: 4/20 = 0.2, not 0.4 (3 ✗). 1 and 2.
8 In a bag of buttons, P(blue) = 0.2, red is twice as likely as blue, P(green) = 0.3, and the rest are yellow. Find P(red) and P(yellow).
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Red = 0.4. 0.2 + 0.4 + 0.3 = 0.9, so yellow = 0.1.
9 A spinner has 8 equal sectors and 3 are shaded. What is the probability of landing on a shaded sector, as a decimal?
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3/8 = 0.375.