# How do I calculate the expected value of a binomial distribution for a genetics example?

I have model with 20 genes which can take on a value of 1 or 0 (the alleles). What is their expected value and variance assuming the alleles are selected with equal probability?

Is this just a binomial distribution?

• You need to know whether those genes take on the values independently. Is that the case or not?
– whuber
Mar 25, 2020 at 18:26
• Yes, their values are assigned independently Mar 25, 2020 at 18:44

Yes, assuming independence and equal probabilities, this is just the binomial distribution. So the number of alleles of value 1 is $$X\sim \mathcal{Binom}(20,p)$$.