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this is a tricky problem, plesse help! 

 

A bacteria population decreases at a rate of 8.5% per hour. There are 650 bacteria present at the start.

 

a) write an equation that describes this population decay. what domain and range make sense for the situation?

b) graph the function in a

c) graph the horizontal line representing half the starting amount of bacteria. find intersection.

d) what is the real world meaning?

 

if you can solve all of this you are better then a retired math teacher! (AKA my dad)

Guest Feb 24, 2017
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8.5%   means that, every hour, there are  91.5% remaining from the previous hour.........so the function is  :

 

y =  650(.915)^x       where y is the number of bacteria present after x hours

 

The domain is [0, infinity (theoretically) )

The range is (0, 650]

 

Here's the graph : https://www.desmos.com/calculator/pwxvqmil5o

 

Half of the bacteria remains when y = 325........this occurs at about 7.8 hours from the start

 

 

cool cool cool

CPhill  Feb 24, 2017

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