User Portlet User Portlet

Discussions
The following does not work: Solve[Sum[(-1)^(k-1)*Binomial[71,k]*(1-(71-k)/71)^n,{k,1,71}]=0.5,n] I want to find the smallest value for n where that sum will yield at least 0.5. But, when I enter that formula, Mathematica tells me, ...