Problem Analysis #25

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Problem Statement

Suppose the following conditions hold. A prize-drawing event uses a box containing 4 crimson balls and 5 blue balls. You are given four opportunities to draw a ball, without replacement.Under these conditions, you receive a prize of 100(10,000-won units) if you draw a crimson ball on the first draw, and 200(10,000-won units) if you draw a crimson ball on the fourth draw. Let XX be the random variable representing the total prize money obtained after drawing four balls from the box. If the expected value of XX is written aspq,\frac{p}{q},where pp and qq are relatively prime positive integers, find the value ofpq2.p \cdot q^2.oindent

Ground Truth
3600
Execution Trace
Reasoning Process

[THOUGHT] I will compute the expected prize using linearity of expectation and verify with Python by enumerating all permutations of draws from the 9 balls (4 crimson, 5 blue). Then I will express the expected value as p/q in lowest terms and compute p*q^2. [/THOUGHT] [PYTHON] import itertools from fractions import Fraction

Represent crimson as 'C' and blue as 'B'

balls = ['C'] * 4 + ['B'] * 5

total_prize = Fraction(0, 1) count = 0

for draws in set(itertools.permutations(balls, 4)): # Prize: 100 if first is crimson, 200 if fourth is crimson prize = 0 if draws[0] == 'C': prize += 100 if draws[3] == 'C': prize += 200 total_prize += prize count += 1

expected_value = total_prize / count print("Expected value as Fraction:", expected_value)

Extract p and q

p = expected_value.numerator q = expected_value.denominator print("p:", p, "q:", q) print("p * q^2:", p * q * q)

Tool Output
[PYTHON OUTPUT] Expected value as Fraction: 150 p: 150 q: 1 p * q^2: 150 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] Using the valid Python output, the expected value is 150 = 150/1, so p = 150 and q = 1, giving p·q² = 150. \boxed{150}

Final Model Output
150

Comparative Analysis (P25) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
35.8
Grok-4.1-fast
31.5
HCX-007(high)
28.2
Deepseek-V3.2
27.9
Llama-VARCO-8B-Instruct
27.7
Solar-Pro-2 (31B)(high)
24.3
Claude-Opus-4.5
14.3
A.X-4.0 (72B)
13.5
GPT-5.1 (high)
13.4
EXAONE-4.0.1-32B (high)
3.9

Avg Token Usage

Gemini-3-Pro-Preview
5595.0
Grok-4.1-fast
5445.0
Solar-Pro-2 (31B)(high)
5220.0
HCX-007(high)
4007.0
Claude-Opus-4.5
3853.0
Deepseek-V3.2
3682.0
EXAONE-4.0.1-32B (high)
3480.0
GPT-5.1 (high)
2933.0
Llama-VARCO-8B-Instruct
1847.0
A.X-4.0 (72B)
1715.0