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4MA1/1FR Jun 2019, Question 9: Basic Probability

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

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The question, in short

Bag has 11 counters: 3 purple, 2 orange, 6 white. Find probabilities for orange, not white, green. Then box of 12 cars with extra red cars added; yellow probability becomes 1/6. Find extra red cars.

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Part (ai) · 1 mark

Find the probability that a randomly taken counter is orange.

  1. 1There are 2 orange counters out of 11 total counters.
  2. 22 / 11 = 2/11

Answer2/11

Part (aii) · 1 mark

Find the probability that a randomly taken counter is not white.

  1. 1There are 6 white counters, so 11 − 6 = 5 counters that are not white.
  2. 25 / 11 = 5/11

Answer5/11

Part (aiii) · 1 mark

Find the probability that a randomly taken counter is green.

  1. 1There are no green counters in the bag.
  2. 20 / 11 = 0

Answer0

Part (b) · 2 marks

With 3 red, 4 blue, 5 yellow cars and extra red cars added, yellow probability is 1/6. Find the number of extra red cars.

  1. 1Let x be the number of extra red cars, so there are 12 + x cars
  2. 2P(yellow) = 5/(12 + x) = 1/6
  3. 312 + x = 5 × 6 = 30, so x = 18

Answer18

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