Lunch with Muhammad
Discrete Mathematics
Level
4
A newly-opened restaurant has \( 5 \) menu items. If the first \( 4 \) customers each choose one menu item uniformly at random, the probability that the \( 4 \)th customer orders a previously unordered item is \( \frac{a}{b} \), where \( a \) and \( b \) are relatively prime positive integers. What is \( a+b \)?
This problem is posed by Muhammad A.
by
Calvin Lin