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Question 377265: Ten minutes after Sasha's little brother left home for karate class, Sasha saw that he forgot his karate uniform, and she ran after him. If Sasha runs twice as fast as her little brother, how long will it take her to reach him? Justify your answer.
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Ten minutes after Sasha's little brother left home for karate class, Sasha saw that he forgot his karate uniform, and she ran after him. If Sasha runs twice as fast as her little brother, how long will it take her to reach him? Justify your answer.
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In 10 minutes, her brother has gone
d = rt = r1*10 where his rate = r1
Sasha is gaining on him at the same rate he's travelling, r1 ( = 2r1 - r1 )
He's 10*r1 away, it'll take her 10*r1/r1 = 10 minutes to catch him.
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