Jenny is setting up a stall offering prizes in a community hall.
She has a bag of white, red, green and black balls. All the balls in the bag are the same size.
A player pays £1 to select a ball at random. The probability that a player selects: • a white ball is 0∙4, • a red ball is 0∙2, • a green ball is 3 times the probability of selecting a black ball.
When either a black ball or a red ball is selected the player will win a prize. The prizes are: • £2.50 for selecting a black ball, • £1.50 for selecting a red ball.
Any ball selected is to be placed back into the bag before the next player has a go.
If 300 players select a ball, show that Jenny can expect to make a profit in excess of £125.