The count in a culture of bacteria was 400 after 3 hours and 25,600 after 6 hours. What is the relative rate of growth? Also, find the function that models the number of bacteria.

Question

The count in a culture of bacteria was 400 after 3 hours and 25,600 after 6 hours. What is the relative rate of growth?  Also, find the function that models the number of bacteria.

anonymous · Answer

Hello jah!  good to see you!

anonymous · Answer

lol good to c u 2 ashes

anonymous · Answer

oops 400 after 2 hours

anonymous · Answer

hmm rate of growth is usually exponential. im tryin to remember the formula tho

anonymous · Answer

there are a couple multiple choice answers...  maybe it will spark the memory

anonymous · Answer

100e^-0.0231t ; rate= 2.22s
or
100e^-0.0231t; rate= 129.6 s

anonymous · Answer

general exponential equation is  y=a*b^t

anonymous · Answer

hmmm or we have which looks like the correct equation
n(t) = pe^(rt)

anonymous · Answer

ooh gave the wrong multiple choices earlier :( sorry

anonymous · Answer

lol i was just about to say

anonymous · Answer

would be
r=1.0397; n(t)=100e^1.0397t
or
r=1.0397; n(t)=400e^1.0397t

anonymous · Answer

yes my apologies
making you work harder and wasting your time   sorry

anonymous · Answer

well the 2nd 1 doesnt make sense just by looking at it so im confident its the 1st 1

anonymous · Answer

believe it is the first one

anonymous · Answer

same

anonymous · Answer

I have a similar one if you have the time

anonymous · Answer

surei have like 10 mins

anonymous · Answer

or prefer me to repost?

anonymous · Answer

Radium-221 has a half life of 30 seconds.  Find a function that models the mass remaining after t seconds given a 100g sample.  Also, find how long it will take for 95% of the sample to decay.

anonymous · Answer

this goes to the multiple choice I posted first

anonymous · Answer

the 1 with 129.6 seconds

anonymous · Answer

thats how long it would take 95% to decay

anonymous · Answer

how did you come up with it if you dont mind?

anonymous · Answer

and I cant give you another medal lol

anonymous · Answer

well since the answer in the multiple choice is the same u can use that formula but for half life i like the formula:
Amount remaining=(original amount)/(2^(t/decay time))
so u just plug it in and solve
95% is gone so 5% remain or 5 grams since its out of 100
5=100/(2^(t/30))

anonymous · Answer

solve for t and its ok lol i dont really do this for the medals anyway :)

anonymous · Answer

oooh that helps a ton... thank you.  Somehow I missed the other question so will rerwork that

anonymous · Answer

the 1 before was wrong?

anonymous · Answer

yes...  not sure why

anonymous · Answer

the only difference is the 100 and the 400 right? which did u choose?

anonymous · Answer

the 1 with 100 should b right... hmm mayb re-post and ask again