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View Full Version : Probability with eliminations?


Wynce
Apr 13, 2014, 10:05 PM
How do you calculate probability in a situation such as the following?

(I can't think of an analogy that works, so bear with me.)

Pokemon A has 6 out of 6 perfect stats.
Pokemon B has 5 out of 6 perfect stats.

If Pokemon A and Pokemon B were to have a child that would inherit 5 random stats from the two parents, with no overlap, what are the odds the flawed stat from Pokemon B would NOT be selected?

Just to clarify, I mean if Stat A is chosen from Pokemon A, Stat A is also eliminated as an option from Pokemon B.

The stats are chosen one at a time.

If you could walk me through the steps, that would be amazing. I'm one of those people who will be driven insane until I know the method.

ebaines
Apr 14, 2014, 06:03 AM
It's easier to think in terms of the probability of the bad stat being selected, as oposed to the bad stat not being selected. Since there are 6 types of stats, and only 5 are being selected, there is a 5/6 probability that the bad stat type is going to be selected. Now that stat may come from Pokemon A or Pokemon B, so there is a 1/2 probability that the stat is selected from B and is therefore bad. Hence the probability for having the bad stat is (5/6)(1/2) = 5/12. The probability that all stats are good is 1 minus that, or 7/12.

You can also do this in terms of the bad stat being left out. There is a 1/6 probability that the bad stat type is not selected. If it is selected, there is a 1/2 probability that the good one is selcted. So the total probability fo getting all good stats is 1/6 + (5/6)(1/2) = 7/12.

Another way to