Question

What is the doubling time of bacteria if you start with two bacteria and there are 128 bacteria after 3hrs?

A) 15min
B) 30min
C) 45min
D) 1hr

Please explain step by step and how you got the answer. Thank you

Answer 1

B) 30min

Explanation:

Start with 2 and continue to multiply that by 2 until you get 128

2 x 2 = 4

4 x 2 = 8

8 x 2 = 16

16 x 2 = 32

32 x 2 = 64

64 x 2 = 128

Then start with what you think could be the right answer based on how many intervals there are.

You know it can't be 15 because there definitely isn't enough and you know its not 1hr because theres way more than 3.

So you're left with either B) 30min or C) 45min

It has to be B) 30min because there are 6 intervals and 30min goes into an hour twice, meaning that if every 2 intervals is an hour there are 3 hours.