9709 P61 - Jun 2019 - Q6
2904
At a funfair, Amy pays $1 for two attempts to make a bell ring by shooting at it with a water pistol.
- If she makes the bell ring on her first attempt, she receives $3 and stops playing. This means that overall she has gained $2.
- If she makes the bell ring on her second attempt, she receives $1.50 and stops playing. This means that overall she has gained $0.50.
- If she does not make the bell ring in the two attempts, she has lost her original $1.
The probability that Amy makes the bell ring on any attempt is 0.2, independently of other attempts.
- Show that the probability that Amy loses her original $1 is 0.64. [2]
- Complete the probability distribution table for the amount that Amy gains. [4]
- Calculate Amy’s expected gain. [1]
