A scientist counts 35 bacteria present in a culture and finds that the number of bacteria triples each hour. The function y = 35 • 3x models the number of bacteria after x hours. Estimate when there will be about 550 bacteria in the culture.

Question

pfenn1 · Answer

The equation is given$$y=35 \times 3x$$where y is the number of bacteria after x hours. To estimate when there will be about 550 bacteria, solve...$$550=35 \times 3x$$Rearrange and solve for x.

anonymous · Answer

$$550=35\times3^x$$ divide by 35 get 
$$\frac{110}{7}=3^x$$ use change of base get 
$$\frac{\ln(\frac{110}{7})}{\ln(3)}$$ then a calculator

anonymous · Answer

if it says "triples every hour" then the model is 
$$35\times 3^x$$ not $$35\times 3x$$

pfenn1 · Answer

@satellite73, thanks.  I guess I read the equation wrong.

anonymous · Answer

no you read what was written, but that was wrong.  hard to write exponents with no symbol palette

pfenn1 · Answer

Well thanks for clearing that up @satellite73