Question 234 of 480
If Log102 = 0.3010 and Log103 = 0.4771, evaluate Log104.5
- A. 0.9542
- B. 0.6532
- C. 0.4771
- D. 0.3010
Correct Answer:
B
Explanation
To evaluate \( \log_{10} 4.5 \) using the given logarithm values, we can break down \( 4.5 \) into its prime factors.
### Step 1: Express \( 4.5 \) in terms of known logarithms
We can express \( 4.5 \) as:
\[
4.5 = \frac{9}{2} = \frac{3^2}{2}
\]
This means we can use the properties of logarithms to find \( \log_{10} 4.5 \).
### Step 2: Apply the logarithm properties
Using the property of logarithms that states \( \log(a/b) = \log a - \log b \) and \( \log(a^b) = b \cdot \log a \), we can write:
\[
\log_{10} 4.5 = \log_{10} \left( \frac{3^2}{2} \right) = \log_{10} (3^2) - \log_{10} (2)
\]
This simplifies to:
\[
\log_{10} 4.5 = 2 \cdot \log_{10} 3 - \log_{10} 2
\]
### Step 3: Substitute the known values
Now we can substitute the known values:
- \( \log_{10} 2 = 0.3010 \)
- \( \log_{10} 3 = 0.4771 \)
Substituting these values into our equation gives:
\[
\log_{10} 4.5 = 2 \cdot 0.4771 - 0.3010
\]
### Step 4: Perform the calculations
Calculating \( 2 \cdot 0.4771 \):
\[
2 \cdot 0.4771 = 0.9542
\]
Now, subtract \( 0.3010 \):
\[
0.9542 - 0.3010 = 0.6532
\]
### Final Answer
Thus, we find that:
\[
\log_{10} 4.5 = 0.6532
\]
The correct option is **B. 0.6532**.
### Explanation of Other Options
- **Option A (0.9542)**: This value represents \( 2 \cdot \log_{10} 3 \) but does not account for the subtraction of \( \log_{10} 2 \).
- **Option C (0.4771)**: This is simply \( \log_{10} 3 \) and does not relate to \( 4.5 \) at all.
- **Option D (0.3010)**: This is \( \log_{10} 2 \) and does not represent \( 4.5 \).
### Summary
- To find \( \log_{10} 4.5 \), express it in terms of known logarithms.
- Use the properties of logarithms to simplify the expression.
- Substitute the known logarithm values and perform the calculations carefully.
- The correct answer is \( \log_{10} 4.5 = 0.6532 \).
### Revision Points
- Remember the properties of logarithms: \( \log(a/b) = \log a - \log b \) and \( \log(a^b) = b \cdot \log a \).
- Always check your calculations step-by-step to avoid simple arithmetic errors.
- Familiarize yourself with common logarithm values for quick reference.
- Practice breaking down numbers into their prime factors to simplify logarithmic evaluations.