The mean length of an object is 5 cm. Which of the following measurements is most accurate?

Options

A. 4.9 cm
B. 4.805 cm
C. 5.25 cm
D. 5.4 cm

Explanation

To determine which measurement is the most accurate compared to the mean length of an object (5 cm), we need to calculate the absolute error for each measurement provided. The measurement with the least absolute error is considered the most accurate.

### Step-by-Step Solution:

1. **Identify the Mean Length**:
The mean length of the object is given as 5 cm.

2. **List the Measurements**:
We need to evaluate the following measurements:
- Option 1: 4.9 cm
- Option 2: 4.805 cm
- Option 3: 5.25 cm
- Option 4: 5.4 cm

3. **Calculate Absolute Error for Each Measurement**:
- For Option 1 (4.9 cm):
\[ \text{Absolute Error} = |5 - 4.9| = 0.1 \text{ cm} \]
- For Option 2 (4.805 cm):
\[ \text{Absolute Error} = |5 - 4.805| = 0.195 \text{ cm} \]
- For Option 3 (5.25 cm):
\[ \text{Absolute Error} = |5 - 5.25| = 0.25 \text{ cm} \]
- For Option 4 (5.4 cm):
\[ \text{Absolute Error} = |5 - 5.4| = 0.4 \text{ cm} \]

4. **Compare the Absolute Errors**:
- Option 1: 0.1 cm
- Option 2: 0.195 cm
- Option 3: 0.25 cm
- Option 4: 0.4 cm

5. **Determine the Most Accurate Measurement**:
The measurement with the least absolute error is Option 1 (4.9 cm) with an absolute error of 0.1 cm. Therefore, the most accurate measurement is:
\[ \text{Most Accurate Measurement} = 4.9 \text{ cm} \]

### Final Answer:
The most accurate measurement is **4.9 cm**.