Skip to content / Đến nội dung
ThichHocToan.com

MathNet 2020 — Math Olympiad Vault — Part 03 Question 52

Math Olympiad Vault · MathNet 2020 — Math Olympiad Vault — Part 03

Question 52

You have six blocks in a row, labeled $1$ through $6$, each with weight $1$. Call two blocks $x \leq y$ connected when, for all $x \leq z \leq y$, block $z$ has not been removed. While there is still at least one block remaining, you choose a remaining block uniformly at random and remove it. The cost of this operation is the sum of the weights of the blocks that are connected to the block being removed, including itself. Compute the expected total cost of removing all the blocks.