9. Gari is seated in a jeep, and at the moment, has one 10 -peso coin, two 5 -peso coins, and six 1-peso coins in his pocket. If he picks four coins at random from his pocket, what is the probability that these will be enough to pay for his jeepney fare of 8 pesos?
Answer: $\frac{37}{42}$
Solution: The only way that Gari will be unable to pay for the fare is if all four coins are 1-peso coins. This has probability $\left.\frac{\left(\begin{array}{l}6 \\ (4 \\ 9\end{array}\right)}{4}\right)=\frac{5}{42}$, so there is a $\frac{37}{42}$ chance that it will be enough to pay for his fare.