A type of bacteria have a division time of 30 minutes. If the population starts with 100 cells, how many bacteria cells would be there after 4h?

Sure, here's how you can calculate it:

1. First, determine how many division cycles occur in 4 hours. Since each division cycle is 30 minutes, and there are 60 minutes in an hour, there are 2 division cycles per hour. Therefore, in 4 hours, there would be 4 * 2 = 8 division cycles.

2. The population of bacteria doubles with each division cycle. So, if you start with 100 cells, after one division cycle, you would have 100 * 2 = 200 cells.

3. After two division cycles, you would have 200 * 2 = 400 cells.

4. You would continue this process for all 8 division cycles.

5. Therefore, after 8 division cycles, you would have 100 * 2^8 = 25,600 cells.

So, there would be 25,600 bacteria cells after 4 hours.