#!/usr/local/bin/node
function root_mean_square(ary) {
    var sum_of_squares = ary.reduce(
        function(s,x) {return (s + x*x)}, 0
    );
    return Math.sqrt(
        sum_of_squares / ary.length
    );
}
 
print( root_mean_square(
    [1,2,3,4,5,6,7,8,9,10]
) );