Suppose that we have a computer server. The probability that server works normally is p. Also we use n copies of the server in order to increase its reliability. What is the chance the whole system works normally ?
There are 5 choices:
1) (p-1)^n 2) 1 - (1-p)^n 3) 1 - p^n 4) p^n - 1 5) (1-p)^n - 1.
So,i think that 4 & 5 are stupid choices because there can come up a negative probability result. Also 1 just looks wrong because if we increase n the probability goes down, and it should be the other way around. My intuition tells me that 2 is the correct , but at the same time i cant reject 3.