Para preparar el menú de un batallón de 136 soldados se necesitan 34kg de arroz
¿a cuantos soldados se le puede prepar el menú con 7kg de arroz?

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?