A bacteria population increases every hour. At 12pm there are 5 cells. At 1pm there are 10 cells. At

A bacteria population increases every hour. At 12pm there are 5 cells. At 1pm there are 10 cells. At 2pm there are 20 cells. At 3pm there are 40 cells. If this pattern continues, how many cells will there be at 7pm?

The bacteria cells double each hour in the example above.

From 3pm to 7pm, we have 4 hours, meaning 4 doubling periods. Which is 2 * 2 * 2 * 2 or 2^4.
So we have:
40 * 2^4
40 * 16 = 640 cells