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You can run 8.0 m/s, 20% faster than your brother. How much head start should you give...

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cake12 | eNotes Newbie

Posted September 2, 2013 at 9:15 AM via web

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You can run 8.0 m/s, 20% faster than your brother. How much head start should you give him in order to have a tie race over 150 m?

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted September 2, 2013 at 9:24 AM (Answer #1)

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"You can run `8.0 m/s, 20%` faster than your brother"

This means when your brother runs 100m you can run 120m.

Your speed is 8m/s. Now we know that your brothers speed is `20%` less than your speed.

Speed of your brother `= 8-8xx20/100 = 6.4m/s`

Time required brother to run 150m `= 150/6.4s = 23.4375`

Time required to you to go 150m `= 150/8 = 18.75`

Head start for brother `= 23.4375-18.75 = 4.6825~=4.6`

So you need to give approximately 4.6 head start for brother.

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