Réponse :
Explications étape par étape :
■ 2 Rouges + 6 Vertes + 4 Bleues = 12 boules
■ il reste seulement 11 boules
pour le tirage de la seconde boule !
■ proba(RR) = 2/12 * 1/11 = 1/66
proba(RV) = 1/6 * 6/11 = 1/11 = 6/66
proba(RB) = 1/6 * 4/11 = 2/33 = 4/66
proba(VR) = 1/2 * 2/11 = 1/11 = 6/66
proba(VV) = 1/2 * 5/11 = 5/22 = 15/66
proba(VB) = 1/2 * 4/11 = 2/11 = 12/66
proba(BR) = 1/3 * 2/11 = 2/33 = 4/66
proba(BV) = 1/3 * 6/11 = 2/11 = 12/66
proba(BB) = 1/3 * 3/11 = 1/11 = 6/66
■ vérif :
proba TOTALE = 66/66 = 1 ♥
