  Let $v_1$, $v_2$, ..., $v_n$ be real numbers whose squares add up to 1.
Consider the $2^n$ signed sums of the form $S = \sum \pm v_i$. Boppana and
Holzman (2017) proved that at least 13/32 of these sums satisfy $|S| \le 1$.
Here we improve their bound to $0.427685$.
