Question

A colony of bacterial doubled every week. If the colony began with 40 bacteria, how many bacteria are present after 4 weeks?

Answer 1

640 bacteria.

Explanation:

Make a chart.

Bacteria Weeks

40 0

80 1

160 2

320 3

640 4

It starts off with 40 bacteria, which means no weeks have passed so far. That is why 40 pairs with 0 rather than 1.