Easily readable, numerically scaled thermometers must be accurate to plus or minus how many degrees Fahrenheit for dishwashing machine water?

• A. 2
• B. 3
• C. 4
• D. 5

Answer: (C)

The measurement skill being tested is how accurately a thermometer used to verify dishwashing water must read. For easily readable, numerically scaled thermometers, the acceptable reading error is plus or minus four degrees Fahrenheit. This means the actual water temperature can be up to four degrees lower or higher than what the thermometer shows, and still be considered acceptable for the sanitizing rinse.

Why this fits: dishwashing water must reach a sanitizing temperature, often around 180°F for the final rinse in high-temperature machines. A tolerance of four degrees provides a practical, reliable margin in busy kitchens where readings can drift due to placement, movement, or thermometer design. It balances accuracy with real-world usability.

Why not a tighter or looser tolerance: a tighter tolerance, like two degrees, would be harder to maintain consistently with everyday thermometers in a fast-paced environment. A looser tolerance, like five degrees, increases the risk that the water is below the safe sanitizing temperature. Four degrees is the standard middle ground that ensures safety while remaining practical.