Question 118 of 480
Without using tables, evaluate \((343)^{\frac{1}{3}} \times (0.14)^{-1} \times (25)^{-\frac{1}{2}}\)
Correct Answer:
A
Explanation
To evaluate the expression \((343)^{\frac{1}{3}} \times (0.14)^{-1} \times (25)^{-\frac{1}{2}}\), we will break it down step by step.
### Step 1: Evaluate \((343)^{\frac{1}{3}}\)
The expression \((343)^{\frac{1}{3}}\) represents the cube root of 343. We need to find a number that, when multiplied by itself three times, equals 343.
- **Finding the cube root**:
- We can factor 343. It can be expressed as \(7 \times 7 \times 7\) or \(7^3\).
- Therefore, \((343)^{\frac{1}{3}} = (7^3)^{\frac{1}{3}} = 7\).
### Step 2: Evaluate \((0.14)^{-1}\)
The expression \((0.14)^{-1}\) is the reciprocal of 0.14.
- **Finding the reciprocal**:
- The reciprocal of a number \(x\) is \(\frac{1}{x}\).
- Thus, \((0.14)^{-1} = \frac{1}{0.14}\).
- To convert 0.14 to a fraction, we can write it as \(\frac{14}{100} = \frac{7}{50}\).
- Therefore, \((0.14)^{-1} = \frac{50}{7}\).
### Step 3: Evaluate \((25)^{-\frac{1}{2}}\)
The expression \((25)^{-\frac{1}{2}}\) represents the negative square root of 25.
- **Finding the square root**:
- The square root of 25 is 5, since \(5 \times 5 = 25\).
- Therefore, \((25)^{-\frac{1}{2}} = \frac{1}{(25)^{\frac{1}{2}}} = \frac{1}{5}\).
### Step 4: Combine all parts
Now we can combine all the evaluated parts:
\[
(343)^{\frac{1}{3}} \times (0.14)^{-1} \times (25)^{-\frac{1}{2}} = 7 \times \frac{50}{7} \times \frac{1}{5}
\]
### Step 5: Simplify the expression
1. **Multiply \(7\) and \(\frac{50}{7}\)**:
- The \(7\) in the numerator and denominator cancels out:
\[
7 \times \frac{50}{7} = 50
\]
2. **Now multiply by \(\frac{1}{5}\)**:
\[
50 \times \frac{1}{5} = \frac{50}{5} = 10
\]
### Final Answer
Thus, the final answer is \(10\).
### Explanation of Options
- **Option A: 10** - This is the correct answer as we have calculated.
- **Option B: 12** - This is incorrect because it does not match our calculations.
- **Option C: 8** - This is also incorrect; it does not correspond to any part of our evaluation.
- **Option D: 7** - This is incorrect as it only represents the cube root of 343, not the entire expression.
### Revision Summary
- The cube root of 343 is \(7\).
- The reciprocal of \(0.14\) is \(\frac{50}{7}\).
- The negative square root of \(25\) is \(\frac{1}{5}\).
- Combining these gives \(10\) as the final answer.