Calculate the error (mm) in the linear measurement of offset, if the length of the offset is 80 m, then the accuracy in the measurement of the length is 1 cm in 60 m.

🧮 Understanding Measurement Accuracy

This question deals with proportional error. The accuracy is given as a ratio (1 cm of error for every 60 m of measurement). To find the error for a different length (80 m), we can set up a simple proportion.

🔬 Detailed Calculation

We are given the following information:

• Accuracy: 1 cm error per 60 m length.
• Measured Length: 80 m.

We can calculate the expected error for the 80 m offset as follows:

The question asks for the answer in millimeters (mm). To convert from centimeters (cm) to millimeters, we multiply by 10:

Therefore, the closest answer is 13.3 mm.

💡 Study Tips

• Proportionality is Key: Recognize that this is a ratio problem. Set up the proportion carefully to find the unknown error.
• Watch Your Units: The most common mistake in such problems is a unit conversion error. The accuracy is in 'cm per m', and the final answer is required in 'mm'. Always double-check your conversions.
• Estimate First: Since 80 m is a bit more than 60 m, you should expect the error to be a bit more than 1 cm (or 10 mm). This quick mental check helps eliminate obviously wrong answers like 0.075 or 7.5.