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Weekly Problem 31 - 2012

Weekly Problem 31 - 2012

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Weekly Problem 32 - 2012

Weekly Problem 32 - 2012

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Weekly Problem 34 - 2012

Weekly Problem 34 - 2012

Weekly Problem 33 - 2012

Stage: 3 Challenge Level: Challenge Level:1

After a year's training, Minnie Midriffe increased her average speed in the London Marathon by $25\%$.

By what percentage did her time decrease?
 
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.

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