Question

A bag contains 3 black balls.Paul picks a ball at random from the bag and without replaces it back in the bag.He mixes the balls in the bag and then picks another ball at random from the bag

(a) one of each colour

Answer 1

A bag contains 3 black balls and 5 white balls. Paul picks a ball at random from the bag and without replaces it back in the bag. He mixes the balls in the bag and then picks another ball at random from the bag.

(a) one of each colour

$$P(black \ and \ white)={3 \over 8}\cdot{5\over 8}+{5 \over 8}\cdot{3 \over 8}={15 \over 32}=0.46875$$