Answer:
£15
Step-by-step explanation:
There are 3 ways to get 7 out of the 12 possible outcomes, so the probability a player will win 30p is 1/4. That is a player will have expected winnings of (1/4)(30p) = 7.5p each time the game is played.
The school gains 20p from each player, but has an expected payout to the player of 7.5p, so the net gain per game to the school is ...
20p -7.5p = 12.5p
The gain to the school when 120 people play is ...
(120)(12.5p) = 1500p = £15 . . . . expected to be raised
