Problem Analysis #25

Solar-Pro-2 (31B)(high) · Run 1

24.25s
5,220 toks
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 as

pq,\frac{p}{q},

where pp and qq are relatively prime positive integers, find the value of

pq2.p \cdot q^2.

oindent

Ground Truth
3600
Execution Trace
Reasoning Process

[THOUGHT] To find the expected value of the total prize money XX, we use the linearity of expectation. The prize is 100 if the first draw is crimson and 200 if the fourth draw is crimson. The expected value E[X]E[X] is the sum of the expected values for each prize.

  1. Probability of drawing a crimson ball on the first draw: There are 4 crimson balls out of 9 total, so the probability is 49\frac{4}{9}.
  2. Probability of drawing a crimson ball on the fourth draw: Due to symmetry in permutations without replacement, this probability is also 49\frac{4}{9}.

Thus, the expected value is:

E[X]=10049+20049=400+8009=12009=4003E[X] = 100 \cdot \frac{4}{9} + 200 \cdot \frac{4}{9} = \frac{400 + 800}{9} = \frac{1200}{9} = \frac{400}{3}

Here, p=400p = 400 and q=3q = 3, which are coprime. Therefore, pq2=40032=3600p \cdot q^2 = 400 \cdot 3^2 = 3600.

[/THOUGHT] [PYTHON] from fractions import Fraction

Calculate expected value components

e1 = Fraction(4, 9) * 100 e4 = Fraction(4, 9) * 200 total = e1 + e4

Extract p and q

p = total.numerator q = total.denominator

Compute p * q^2

result = p * (q ** 2) print(result) [/PYTHON]

Tool Output
[PYTHON OUTPUT] 3600 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python output confirms that pq2=3600p \cdot q^2 = 3600. The expected value calculation aligns with the derived fraction 4003\frac{400}{3}, where p=400p = 400 and q=3q = 3. Thus, the final answer is: 3600\boxed{3600} [/THOUGHT]

Final Model Output
3600

Comparative Analysis (P25) (Average across runs)

Avg Time Taken

K-EXAONE-236B-A23B
164.4
Kanana-2-30B-Thinking
45.3
Gemini-3-Pro-Preview
35.8
Grok-4.1-fast
31.5
K-EXAONE-236B-A23B
28.9
HCX-007(high)
28.2
Deepseek-V3.2
27.9
Llama-VARCO-8B-Instruct
27.7
Solar-Pro-2 (31B)(high)
24.3
Kanana-2-30B-Thinking-2601
19.0
Solar-Open-100B
16.4
Claude-Opus-4.5
14.3
A.X-4.0 (72B)
13.5
GPT-5.1 (high)
13.4
GPT-5.2 (high)
11.4
EXAONE-4.0.1-32B (high)
3.9

Avg Token Usage

K-EXAONE-236B-A23B
18,548
Kanana-2-30B-Thinking
9,068
Kanana-2-30B-Thinking-2601
5,759
Gemini-3-Pro-Preview
5,595
Grok-4.1-fast
5,445
Solar-Pro-2 (31B)(high)
5,220
Solar-Open-100B
4,781
K-EXAONE-236B-A23B
4,410
HCX-007(high)
4,007
Claude-Opus-4.5
3,853
Deepseek-V3.2
3,682
EXAONE-4.0.1-32B (high)
3,480
GPT-5.2 (high)
3,140
GPT-5.1 (high)
2,933
Llama-VARCO-8B-Instruct
1,847
A.X-4.0 (72B)
1,715