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Conditional Probability

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Question 7

There are only black socks and blue socks in a drawer. There are 7 black socks and 3 blue socks.

Sophie takes at random a sock from the drawer. She does not put the sock back in the drawer.

Sophie takes at random a second sock from the drawer.

a.

Complete the probability tree diagram.

A probability tree diagram for two socks. The first selection has two branches: Black and Blue, each with a dotted line for probability. The second selection has four branches: Black, Blue, Black, and Blue, each with a dotted line for probability.

[2]
b.

Work out the probability that Sophie takes two socks of the same colour.

[2]

Conditional Probability Questions

  1. GCSE
  2. /Maths
  3. /Conditional Probability

Practise OCR GCSE Maths Conditional Probability with exam-style questions for Foundation and Higher tier. 28 questions, matched to the OCR GCSE Maths (J560) specification and written in the written papers style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

Question bank