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4MA1/1FR Jun 2018, Question 10: Basic Probability

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1FR (Foundation) · Calculator · 5 marks

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The question, in short

Bag X has 20 counters: 7 green, 10 red, rest blue. Find probabilities for red and blue, then compare green-counter probability for Adam drawing from bag Y against Ruth drawing from bag X.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 1 mark

State the probability that a counter drawn at random from bag X is red.

  1. 1There are 10 red counters in bag X.
  2. 2There are 20 counters in total in bag X.
  3. 3Probability = 10 / 20

Answer10/20

Part (b) · 1 mark

Calculate the probability that a counter drawn at random from bag X is blue.

  1. 1Total counters = 20
  2. 2Green counters = 7
  3. 3Red counters = 10
  4. 4Blue counters = 20 − 7 - 10 = 3
  5. 5Probability = 3 / 20

Answer3/20

Part (c) · 3 marks

Using bag Y counts (2 more green, 1 more red, 2 more blue than bag X), decide whether Adam or Ruth has greater probability of drawing green, showing working.

  1. 1Ruth: P(green) = 7/20 = 0.35
  2. 2Bag X blue = 20 − 7 − 10 = 3
  3. 3Bag Y: green 9, red 11, blue 5, total 25
  4. 4Adam: P(green) = 9/25 = 0.36
  5. 50.36 > 0.35, so Adam

AnswerAdam

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