If the variance of 5 values is 0.81, then what is its standard deviation?

Options

A. 0.09
B. 0.9
C. 2.7
D. 0.27

Answer

To find the standard deviation from the given variance, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the relationship between variance and standard deviation**:
- The standard deviation (SD) is the square root of the variance (Var). This can be expressed mathematically as:
\[ \text{SD} = \sqrt{\text{Var}} \]

2. **Identify the given variance**:
- According to the problem, the variance of the 5 values is given as:
\[ \text{Var} = 0.81 \]

3. **Apply the formula to calculate the standard deviation**:
- Substitute the value of variance into the formula:
\[ \text{SD} = \sqrt{0.81} \]

4. **Calculate the square root**:
- The square root of 0.81 can be calculated as:
\[ \text{SD} = 0.9 \]

5. **Conclusion**:
- Therefore, the standard deviation of the given values is:
\[ \text{SD} = 0.9 \]

### Final Answer:
The standard deviation is **0.9**.