Question

A biologist is researching a newly-discovered species of bacteria. He puts 1,000 bacteria into what he has determined to be a favorable growth medium. Twelve hours later, he measures 12,500 bacteria. Assuming exponential growth, find the growth equation and use it to determine the number of bacteria after twenty hours.
A. 20,167
B. 20,864
C. 67,326
D. 78,324

Answer 1

Do it using the same method as last time. Initial Ao is 1000, and then when t=12, A=12500. Plug them into the equation from last time, find r.

Then plug in t=20 after you've done all that.

Answer 2

B!

Answer 3

haha idk. I haven't worked it out yet.

Answer 4

okay let me know once uve worked it out

Answer 5

well r= 0.2148, so if you got that, that's a good sign

Answer 6

yep i did

Answer 7

B isn't correct, though

Answer 8

well for r i did get 0.2148, so maybe I made a mistake somewhere else. hmm

Answer 9

now use the formula, plug in r, and plug in t=20

Answer 10

20,167. my brother helped me so not sure if the answer is correct. Is it?

Answer 11

plug in r and t=20

A = 1000e^(20*0.2148)

idk what you're doing wrong... show me your work.

Answer 12

42960000e

Answer 13

How'd you get that...? You gotta show your work so i can help...

Answer 14

i got the same as you lol; A=1000e(20*0.2148) and when i solved that I got 42960000e

Answer 15

There's no power sign...

1000e^(20*0.2148)

Answer 16

oops sorry forgot to add that

Answer 17

it's pretty important :P

Answer 18

okay than I get 1000e^42960

Answer 19

Where'd 42960 come from?
just type this in a calculator:

1000e^(20*0.2148)

Answer 20

i only have my phone for a calculator, so that prolly whynim getting a different answer

Answer 21

Okay i used a calculator online and got this; 73405.5833378

Answer 22

and im sure we have to round so then that would make our answer D

Answer 23

Yep. Your phone is the problem.

Idk why the answer choices are not right...

Answer 24

yea foreals lol thanks

Answer 25

I'd go with D, tho

Answer 26

yep! thanks:)