Question 272 of 480
Simplify the expression \( (3 \times 10^4) \times (2 \times 10^3) \) and express it in standard form. What is the result?
- \( 6 \times 10^7 \)
- \( 6 \times 10^8 \)
- \( 5.6 \times 10^7 \)
- \( 5.6 \times 10^8 \)
Correct Answer:
B
Explanation
To simplify the expression \( (3 \times 10^4) \times (2 \times 10^3) \) and express it in standard form, let's break it down step-by-step.
### Step 1: Understand the Components
The expression consists of two parts:
- \( 3 \times 10^4 \): This means 3 multiplied by \( 10^4 \) (which is 10,000).
- \( 2 \times 10^3 \): This means 2 multiplied by \( 10^3 \) (which is 1,000).
### Step 2: Multiply the Coefficients
First, we multiply the numerical coefficients (the numbers in front):
\[
3 \times 2 = 6
\]
### Step 3: Multiply the Powers of Ten
Next, we multiply the powers of ten. When multiplying powers of ten, we add the exponents:
\[
10^4 \times 10^3 = 10^{4+3} = 10^7
\]
### Step 4: Combine the Results
Now, we combine the results from Steps 2 and 3:
\[
(3 \times 10^4) \times (2 \times 10^3) = 6 \times 10^7
\]
### Step 5: Express in Standard Form
The result \( 6 \times 10^7 \) is already in standard form, which is a number between 1 and 10 multiplied by a power of ten.
### Final Answer
Thus, the simplified expression is:
\[
\boxed{6 \times 10^7}
\]
### Explanation of Other Options
Now, let's analyze the other options to understand why they are incorrect:
- **Option A: \( 6 \times 10^7 \)** - This is actually the correct answer, so it should be noted that the current recorded correct option (B) is incorrect.
- **Option B: \( 6 \times 10^8 \)** - This option is incorrect because it suggests that we added the exponents incorrectly. The correct addition of the exponents is \( 4 + 3 = 7 \), not \( 8 \).
- **Option C: \( 5.6 \times 10^7 \)** - This option is incorrect because it misrepresents the coefficient. The correct coefficient from our multiplication is 6, not 5.6.
- **Option D: \( 5.6 \times 10^8 \)** - This option is incorrect for the same reasons as option B and C. It incorrectly states both the coefficient and the exponent.
### Common Pitfalls
- **Misadding Exponents**: A common mistake is to miscalculate the sum of the exponents when multiplying powers of ten.
- **Incorrect Coefficient**: Sometimes students might confuse the coefficients, especially if they are not careful with their multiplication.
### Revision Summary
- To multiply numbers in scientific notation, multiply the coefficients and add the exponents.
- The result should be expressed in standard form, which is a number between 1 and 10 multiplied by a power of ten.
- Always double-check your calculations for both the coefficients and the exponents to avoid common mistakes.