3. An airplane has 15 seats and 15 passengers, each with an assigned seat (passenger k assigned to seat k). Passenger No.1 boards first but has lost the boarding pass and chooses a seat uniformly at random. Passengers No.2 through No.14 board in order: each takes their assigned seat if available; otherwise, they choose a remaining seat uniformly at random. Passenger No.15 boards last. What is the exact probability that Passenger No.15 sits in the assigned seat (seat No.15)? (10%) (Note: You are asked to answer in percentages, counted to two decimal places.)

4. A prestigious art gallery is hosting an exhibition of 10 sculptures. The gallery has 10 pedestals arranged in a perfect circle. Among these sculptures are three specific pieces created by the same artist (Tom), which we will label A1, A2, and A3. The other seven sculptures are created by seven different artists. The curator has dictated the following strict conditions for the installation: Condition 1: The Artist's Constraint: No two of the Tom's sculptures (A1, A2, A3) can be placed on adjacent pedestals. Condition 2: The Rotational Symmetry: Because the pedestals are in a circle and the room is perfectly uniform, two arrangements are considered identical if one can be rotated into the other. Condition 3: The Reflectionary Constraint: Furthermore, because the room features floor-to-ceiling mirrors on all walls, we must also account for vertical symmetry. Two arrangements are considered identical if one is a reflection of the other. Answer the following two questions. (1) Assuming that A1, A2, and A3 are distinct sculptures, calculate the total number of ways that the 10 sculptures can be arranged on the pedestals while satisfying all three conditions. (20%)

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