Leg It

How far from the finishing line should these runners start to make the race 'fair'?
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Problem



Amina and Bhavi are both training for a 100 metre race. Amina's average time to run 100 metres is 12 seconds, and Bhavi's is 15 seconds. To make their training sessions more competitive, they want to run 'fair' races against each other - so that if they ran at their average speeds, they would finish at the same time.

a) If Amina starts 100 metres from the finish line, how many metres in front of her should Bhavi start to make the race 'fair'?

b) If Bhavi starts 100 metres from the finish line, how many metres behind her should Amina start to make the race 'fair'?