sets of 
 trials each, with the probability of success 
 constant in each set.
where 
 is the variance of 
.
 
	    
	
    
 sets of 
 trials each, with the probability of success 
 constant in each set.
where 
 is the variance of 
.
Weisstein, Eric W. "Lexis Trials." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/LexisTrials.html