How long will a 1 mm long colony of bacteria be in 1 hour if it triples in length every 15 minutes?

Answer 1

This question takes a little reasoning power. You have to work it through.
First, we establish that there are FOUR fifteen minute periods in every hour.
So in in fifteen minutes, it will triple from 1 to 3 MM long.
In another fifteen minutes, it will triple again, from 3 to 9 mm.
After forty five minutes it goes again, to 27 mm
And finally, at the end of the hour, it triples from 27 mm to 81 mm.