Which of the following measurement is most precise?

Options

A. 5.00 mm
B. 5.00 cm
C. 5.00 m
D. 5.00 km

Explanation

To determine which of the given measurements is the most precise, we need to analyze the precision of each measurement based on the number of decimal places and the smallest unit of measurement.

### Step-by-Step Solution:

1. **Understanding Precision**: Precision in measurements refers to how close multiple measurements are to each other. It is often indicated by the number of decimal places in the measurement. The more decimal places, the more precise the measurement is.

2. **List the Given Measurements**: Assume we have the following measurements (as an example):
- A) 5.00 mm
- B) 10.0 mm
- C) 15 mm
- D) 20.00 mm

3. **Identify Decimal Places**:
- Measurement A (5.00 mm) has 2 decimal places.
- Measurement B (10.0 mm) has 1 decimal place.
- Measurement C (15 mm) has 0 decimal places.
- Measurement D (20.00 mm) has 2 decimal places.

4. **Determine the Smallest Unit of Measurement**: The precision of a measurement can also be indicated by the smallest unit of measurement. In this case, 5.00 mm has the smallest unit (0.01 mm), which indicates a smaller possible error.

5. **Calculate the Possible Error**:
- For 5.00 mm, the commonly accepted error is ±0.01 mm.
- For 10.0 mm, the error is ±0.1 mm.
- For 15 mm, the error is ±1 mm.
- For 20.00 mm, the error is ±0.01 mm.

6. **Compare the Errors**: The measurement with the smallest possible error is the most precise.
- 5.00 mm has an error of ±0.01 mm.
- 10.0 mm has an error of ±0.1 mm.
- 15 mm has an error of ±1 mm.
- 20.00 mm has an error of ±0.01 mm.

7. **Conclusion**: Since 5.00 mm has the smallest unit and the least error, it is the most precise measurement among the given options.

### Final Answer:
The most precise measurement is **5.00 mm**.

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