Edhirpaarkkum mati endpadhu oru yaadhruccha maatriyin saragasamaana mudivaagiradhu, idhu oru summa-aaga ella saadhaarana mudivugalai adhanin nigazhcciyaal paarkkum. Suthiram: E(X) = S [xi x P(xi)]. Udharanamaga, oru sadai aadil: 6 vandhal $5 varukiradhu; vera ellandhaalum $1 pogum. E(X) = (1/6)x$5 + (5/6)x(-$1) = $0. Zero edhirpaarkkum matiyan aadal kanidam needhiyaanadu.