Is an outcome where we draw person A, then B, then C different from an outcome where we draw person C, then A, then B? What could that tell us?
1/84
Practice makes perfect
We want to find the probability that you and your two friends will win the concert tickets. To do it, we will first find in how many ways three individuals can be drawn from a group of 9. Note that, we do not care about the order of those individuals inside a single triple. Therefore, we will use the formula for a combination.
_n C_r = n!/(n-r)!* r!Now, we will use the above formula for combination of n objects taken r at a time. Since we want to draw three people who will receive concert tickets from a group of 9 people, we will substitute n=9 and r=3. Let's do it.
There are 84 possible outcomes, or triples. Out of those possible 84 triples, only one consists of you and your two friends. Therefore, we know the probability of you and your two friends winning the concert tickets.
P(A)=1/84
