148.Absolute Difference of Two 30-Sided Dice
★★★expected valueJane Street
Two fair 30-sided dice, numbered 1 to 30, are rolled. What is the expected value of the absolute difference between the two results?
Sign in to submit an answer and track it toward your stats.
Sign inHint
Count how many of the 900 ordered pairs have each possible gap, then average. The count falls off linearly in the gap.
Want timed drills, mental math, and a market-making game too? Try the full practice suite →