A petri dish contains only two bacteria. The bacteria divide every half hour. How many bacteria will exist after 3 hours?

I thought it'd be 12, but apparently not.

It divides 2 times every hour, so for 3 hours it'll divide 6 times. You start with 2, and every half hour they divide into 2. So that means they divide into 2 a total of 6 times. Soo, that's the original 2 times 2^6. So its 2*64 = 128

A bacteria culture divide each half hour, after 3 hours there are

6400 bacteria, how many bacteria were there to begin with ?

To determine the number of bacteria that will exist after 3 hours, we need to consider the rate at which they divide and multiply.

Given that the bacteria divide every half hour, we can calculate the number of divisions that occur within 3 hours:

Divisions per hour = 1 / (time per division)
Divisions per hour = 1 / (0.5 hours) = 2 divisions per hour

To find the total number of divisions within 3 hours, we multiply the divisions per hour by the number of hours:

Total divisions = divisions per hour × number of hours
Total divisions = 2 divisions per hour × 3 hours = 6 divisions

Since each division results in the bacteria doubling in number, we can calculate the final number of bacteria:

Number of bacteria = 2 (initial bacteria) × 2^total divisions
Number of bacteria = 2 × 2^6 = 2 × 64 = 128 bacteria

Therefore, after 3 hours, there will be 128 bacteria in the petri dish, not 12.

1st hour: 2, 4

2nd hour: 8, 16

3rd hour: 32, 64