In Haskell, map (flip filter list) on a list of predicates is kinda neat.

import Text.Printf
import Data.List (genericLength)

main = do
    len <- readLn :: IO Float
    list <- fmap (map (read :: String -> Int) . words) getLine
    mapM_ (printf "%.6f\n" . (/len) . genericLength . flip filter list) [(>0), (<0), (==0)]