Board Thread:General Discussion/@comment-6182229-20130207070333/@comment-20191493-20130916054815

Hello,

Just like to point some calculation for the probability since I'm engineer too.

For 62 rare card draw:

Chance of 5* = 0.0069

Chance of 1-4* = 1 - 0.0069 = 0.9931

Chance of not getting 5* card in 62 draw = ( 0.9931 ) ^62 = 0.65097584

Chance of getting at least one 5* = 1 - 0.65097584 = 0.349

So you have 35% to get at least one 5* card from 62 rare draw, not 42*.

The mistake in your equation is that you assume

Rylain wrote: That's how it works. Quoted from Wiki:

Mutually exclusive

If either event A or event B or both events occur on a single performance of an experiment this is called the union of events A and B denoted as P(A U B). If two events are mutually exclusive then the probability of either occuring is

P(A or B) = P(A U B) = P(A) + P(B)

For example, the chance of rolling a 1 or 2 on a six-sided fair die is

P(1 or 2) = P(1) + P(2) = (1/6) + (1/6) = (1/3)

Or in this case, the chance of getting a 5* is

P(69/10000) x 62 = 0.69 x 62 = 42.78%

You can use your calculator to verify. "Trust me, I is an engineer" : )