In the sharpeners problem, if the white sharpeners are 10, what is the price of the brown sharpener?

In the sharpeners problem, if the white sharpeners are 10, what is the price of the brown sharpener?

• A. 4
• B. 5
• C. 6
• D. 7

Answer: (B)

This question tests translating a simple proportional relationship into a calculation. If the white sharpener costs twice as much as the brown one, and the white sharpener’s price is 10, then the brown sharpener’s price is half of that. Half of 10 is 5, so the brown sharpener costs 5. Using the idea of proportionality helps: any other value for the brown price would make the white price different from 10 (e.g., if brown were 4, white would be 8; if brown were 6, white would be 12), which doesn’t match the given 10 for the white sharpener.

This question tests translating a simple proportional relationship into a calculation. If the white sharpener costs twice as much as the brown one, and the white sharpener’s price is 10, then the brown sharpener’s price is half of that. Half of 10 is 5, so the brown sharpener costs 5.

Using the idea of proportionality helps: any other value for the brown price would make the white price different from 10 (e.g., if brown were 4, white would be 8; if brown were 6, white would be 12), which doesn’t match the given 10 for the white sharpener.