9709 P6 - Nov 2005 - Q6
2955
In a competition, people pay $1 to throw a ball at a target. If they hit the target on the first throw they receive $5. If they hit it on the second or third throw they receive $3, and if they hit it on the fourth or fifth throw they receive $1. People stop throwing after the first hit, or after 5 throws if no hit is made. Mario has a constant probability of \(\frac{1}{5}\) of hitting the target on any throw, independently of the results of other throws.
- Mario misses with his first and second throws and hits the target with his third throw. State how much profit he has made.
- Show that the probability that Mario’s profit is $0 is 0.184, correct to 3 significant figures.
- Draw up a probability distribution table for Mario’s profit.
- Calculate his expected profit.
