# Math Help - About independent problem

consider n independent trials, each of which results in one of the outcomes 1,...,k with respective probabilities p_1 ,...,p_2, sum of p_i = 1.
Show that if all the p_i are small, them the probability that no trial outcome occurs more than once is approximately equal to
exp(-n(n-1)sum of ((p_i)^2)/2)

2. ## Re: About independent problem

Hey Glitter.

First you should try and write down the PDF (Hint: Look at a multinomial distribution).