How can you throw a ball as hard as you can and have it come back to you, even if it doesn't bounce off anything? There is nothing attached to it, and no one else catches or throws it back to you?

A Petri dish hosts a healthy colony of bacteria. Once a minute every bacterium divides into two. The colony was founded by a single cell at noon. At exactly 12:43 (43 minutes later) the Petri dish was half full.
At what time will the dish be full?

Ready with your answers?


Answer for first question is just throw it straight upwards. It will certainly return back to you.

For the second Question, the answer is "at 12:44" since the bacteria at 12:43 will double after 1 minute