Question

The track team is trying to reduce their time for a relay race. First they reduce their time by 2.1 minutes. Then they are able to reduce that time by 1/10. If their final time is 3.96 minutes, what was their beginning time?

Answer 1

6.5 minutes

Explanation:

Let the initial time be X minutes.

No. of minutes of reduction of time = 2.1

Time left after reduction of 2.1 minutes = (X - 2.1)Minutes

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Fraction of time reduce again 1/10 of time left = (1/10) * (X - 2.1)Minutes

Time left after reduction of (1/10) * (X - 2.1)Minutes

= (X - 2.1)Minutes - {(1/10) * (X - 2.1)Minutes}

=> (1-1/10)*(X - 2.1)Minutes

=> (9/10) * (X - 2.1)Minutes

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Absolute value of time as given in question is 3.96 minutes

therefore, we have

(9/10) * (X - 2.1)Minutes = 3.96 minutes

=> (X - 2.1)Minutes = (10/9) * 3.96 minutes

=> X = 4.4 + 2.1 = 6.5

Therefore the beginning time was 6.5 minutes.