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The bacteria in a jar triple every 20 seconds. After three minutes, there are 275,562 bacteria in the jar. How many were in the jar at the beginning of the experiment?

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Rudram592 Apr 9, 2019

#1**+1 **

The bacteria in a jar triple every 20 seconds. After three minutes, there are 275,562 bacteria in the jar. How many were in the jar at the beginning of the experiment?

Three minutes = 180 seconds

We have this

A = A_{0}(3)^[ ( t / 20 ) where A0 = the original number.....A is the number after t seconds

Filling in what we know.....

275562 = A_{0 }* 3^(180/20 )

275562 = A_{0} * 3^(6) divide both sides by 3^6

275562 / 3^6 = A_{0} = 378

CPhill Apr 9, 2019