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Curt just drank a cup of coffee to help him stay awake. The coffee had 130 milligrams of caffeine in it. If his body processes 7% of the caffeine every hour, how much will be left in 4 hours?

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User Ljtomev
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2 Answers

4 votes
Since we have to multiply it by 0.07 4 times (for each hour), we have 130 * 7^4
User Lataya
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5 votes

Answer:

After 4 hours, there will 91.31 miligrams of caffeine within his body.

Explanation:

Givens

  • Curt drank 130 miligrams of caffeine.
  • His body processes 7% of caffeine everyhour.

If Curt's body processes 7% every hour, we just need to that 7% after each hour. Also, we know that 7% equals 0.07.

First hour.


0.07(130)=9.1ml

The first hour, his body processed 9.1 miligrams, so it remains


130-9.1=120.9ml

There's still 120.9 miligrams in his body.

Second hour.


0.07(120.9)=8.46ml


120.9-8.46=112.44ml

Third hour.


0.07(112.44)=7.87ml


112.44-7.81=104.63ml

Fourth hout.


0.07(104.63)=7.32ml


104.63-7.32=97.31ml

Therefore, after 4 hours, there will 91.31 miligrams of caffeine within his body.

User Tomek Cejner
by
8.2k points
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