Unit 12 · Multi-Step Conditional Reasoning

Maths, Physics, Computing — Find the Impossible Outcome

Lesson 23 of 30

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About this lesson

Four rules govern who passed Maths, Physics and Computing. One of them says passing Maths forces you to pass Computing too. Another says no one passed all three. Together, those two rules make one particular combination impossible — but which one?

Chapters

0:00Introduction
0:22Question
1:07Strategy
1:48Step 1: Write all four rules as arrows
2:33Step 2: Build the 8-combination table
3:54Step 3: Match each option to the valid rows
5:09Correct answer

Question

In end-of-year tests, the following results were achieved by students taking Maths, Physics and Computing:

  • Everyone who passed Physics also passed at least one of the other two subjects.
  • No one who passed Maths failed Computing.
  • No one passed all three subjects.
  • No one failed all three subjects.

Which one of the following is not possible?

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