We read this as the probability of k successes out of N trials given that the probability of one success is p. Binomial mean and standard deviation formulas. The full binomial probability formula with the binomial coefficient is P X n.
PX r n C r p r 1-p n-r.
It is done with the help of the z. Binomial Theorem Step-by-Step Initializing live version. Find X from the question. So it is essential to standardize the observations to be able to compare that.