A scientist counts 35 bacteria present in a culture and finds that the number of bacteria triples each hour. The function y = 35 • 3^x models the number of bacteria after x hours.

Graph the function. (You do not need to submit the graph).

Use the graph to estimate when there will be about 550 bacteria in the culture.

Question

A scientist counts 35 bacteria present in a culture and finds that the number of bacteria triples each hour. The function y = 35 • 3^x models the number of bacteria after x hours.

Graph the function. (You do not need to submit the graph).

Use the graph to estimate when there will be about 550 bacteria in the culture.

directrix · Answer

Isn't this also from night before last? That is, hasn't it been answered?

anonymous · Answer

i answered it but someone got me confused with log and In

directrix · Answer

Was it this thread where you became confused? http://openstudy.com/users/lilyswan#/updates/51671858e4b054d007825f28

anonymous · Answer

yep the same

directrix · Answer

Did you begin with 500 = 35 * 3^x to solve for x? 

(I know you are supposed to read it from the graph but if the question has no answer options, reading values from a hand drawn graph of an exponential function is dicey.

anonymous · Answer

sorry for confusing you

anonymous · Answer

now i started it with 550 = 35*3^x

anonymous · Answer

its alright peter  i just want to clear my confusion its not because of you to be true log and in really confuses me at time

anonymous · Answer

and this question is the tricky one

directrix · Answer

550 = 35*3^x

(1/35) * 550 = (1/35) * 3^x

Do you agree with that. I'm dividing by 35 as did the others.

anonymous · Answer

ok

directrix · Answer

15.714286 (approx)  =  3^x 

Agree?

directrix · Answer

(1/35) * 550 = 15.714286 (approx)

directrix · Answer

@LilySwan

anonymous · Answer

yea i got

directrix · Answer

log (15.714286) = log (3^x)  --> These are base 10 logs.

directrix · Answer

Agree?

anonymous · Answer

ok

directrix · Answer

log (15.714286) = log (3^x)

log (15.714286) = x * (log 3)

anonymous · Answer

1.19=x^0.477

directrix · Answer

Why log (3^x) = x * (log 3)

directrix · Answer

1.19=x^0.477  --> Try not to jump ahead. Be a step-sister. Show all the steps.

anonymous · Answer

ok

directrix · Answer

log (15.714286) = x * (log 3)

1.19629465304 = x * (log 3)

directrix · Answer

1.19629465304 = x * 0.47712125472

anonymous · Answer

ok

directrix · Answer

1.19629465304 divided by .47712125472 = x

directrix · Answer

2.50731788032 = x

anonymous · Answer

ok so we will use log

anonymous · Answer

thanks trix for clearing my doubts

directrix · Answer

x is roughly 2.5 hours required to get 550 bacteria.

anonymous · Answer

thanks

directrix · Answer

Okay, then. Ha sido un placer

anonymous · Answer

ill be back i have to take my medicine in 10 minutes