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Maths Week: Sunday puzzle

Fancy another mathematics challenge? (And get the answer to yesterday’s puzzle.)

Image: Shutterstock/Pavel1964

MATHS WEEK STARTED yesterday and, as is our annual tradition, we’re setting our readers some puzzles. Give them a go!

Day 2

In maths class, we’re used to reducing real world things to numbers and symbols and working on these abstract objects. This has proven to be a very powerful method. In maths drawing a picture or diagram is a very effective way to try to understand a problem. It gets you started working.

Consider the following logic problem.

A report of a race states:

  • Ciara finished ahead of Bill.
  • Bill finished two places behind Anne.
  • Emer finished two places behind Dave.
  • Anne finished behind Ciara.
  • Ciara finished three places ahead of Emer.

Can you figure out the order in which they finish?

Trying to do this in your head is very challenging. Most people will find it helpful, or necessary, to reach for a piece of paper and draw the relative positions.

It’s actually much better if you tear off 5 small pieces of paper and label them with the initials, A, B, C, D, E.

Arrange the pieces according to each statement above and you’ll quickly have the finishing order.

Here’s another one. This has more information so it’s even more difficult to handle it in your head.

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Five people live (in different houses) in a row of houses numbered from left 1-5.

  • Aine’s house has a green door.
  • Bebhin lives to the left of Aine.
  • Chris lives to the left of Aine.
  • Dearbhail’s house has a blue door.
  • Eoghan lives to the right of the blue door.
  • Eoghan lives three houses to the right of the yellow door.
  • The yellow door is immediately left of the pink door.
  • Bebhin’s house doesn’t have a pink door.
  • Aine isn’t in an end house.
  • Who lives in which house and with what colour door?

Come back tomorrow for the answer to today’s puzzle.

Puzzles compiled for The Journal by Eoin Gill of Maths Week Ireland / Waterford Institute of Technology.

Saturday’s puzzle: The answer 

(Brackets are used for clarity)

  • 221 G 12345 … (5*4) + 3+2-1 = 24
  • 221 D 35210 … 3* (5+2+1 + 0) = 24
  • 221 W 23587 … (3*8) + 7 – 5 -2 = 24
  • 221 C 65372 … (6 * 5) – 7 -2 +3 = 24
  • 221 LH 69996 … (9-6 + (9/9))*6 = 24
  • 221 L 1346 … 6/(1-(3/4)) = 24

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