Problem 202 Answer

Question

Every generaion of red amoeba has a 5% chance of spawning 5 more red amoeba, a 10% chance of spawning 3 blue amoeba, a 1% chance of doing both, and a 84% chance of not spawning.

Every generaion of blue amoeba has a 3% chance of spawning 5 more blue amoeba, a 2% chance of spawning 10 red amoeba, a 1% chance of doing both, and a 94% chance of not spawning.

Your petri dish starts with one red amoeba. What is the expected number of red and blue amoeba observed before all amoeba die off?

Answer

One red amoeba will spawn into 800/461 =~ 1.7354 on average.
One red amoeba will spawn into 330/461 =~ 0.7158 blue amoeba on average.

Michael Shackleford, ASA — Apr. 1, 2009