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For younger learners

  • Early Years Foundation Stage

Grandpa's Rock Cakes

Age 11 to 14
ShortChallenge Level Yellow starYellow starYellow star
Secondary curriculum
  • Problem
  • Solutions

Grandpa has made one of his special giant rock cakes.
At his party, five of the guests tried to guess the weight of the cake.

Their guesses were 5 040g, 5 060g, 5 110g, 5 120g and 5 150g.

Actually, none of them was right. Only two were more than 30 grams out, and those guesses were out by 70g and 90g.

What was the weight of the cake?

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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