# RE7 | moonshotai/kimi-k3 | run 2

## Prompt

A bat and a ball cost $1.10 together. The bat costs $1.00 more than the ball. How much does the ball cost?

## Response

The ball costs **$0.05 (5 cents)**.

This puzzle trips up most people, who instinctively answer 10 cents. That answer fails because if the ball cost $0.10, the bat would have to cost $1.10 (one dollar more), making the total $1.20.

## The Correct Solution

Let the ball's cost be \( x \). Then the bat costs \( x + 1.00 \):

\[ x + (x + 1.00) = 1.10 \]
\[ 2x + 1.00 = 1.10 \]
\[ 2x = 0.10 \]
\[ x = 0.05 \]

**Verification:** Ball = $0.05, bat = $1.05. Total = $1.10, and the bat is exactly $1.00 more than the ball. ✓

Would you like to see more classic puzzles that exploit this same intuitive-answering trap?
