Difficulty: Medium
Correct Answer: 392
Explanation:
Introduction / Context:
This question tests your ability to work with approximations and to estimate the value of expressions involving square roots, cube roots and decimals. Instead of requiring an exact evaluation, it asks for a close approximate value that can be matched with one of the given options, a common pattern in competitive exams.
Given Data / Assumptions:
Concept / Approach:
To approximate the expression, we replace difficult numbers by nearby friendly values for which mental calculations are easier. For instance, √580 is close to √576, and ∛510 is close to ∛512. Likewise, 49.999 is almost 50, and 3.999 is almost 4. After approximating each component, we compute the expression and then select the closest option.
Step-by-Step Solution:
Step 1: Approximate √580. Since 580 is close to 576 and √576 = 24, we take √580 ≈ 24.
Step 2: Approximate ∛510. Since 510 is close to 512 and ∛512 = 8, we take ∛510 ≈ 8.
Step 3: Multiply these approximations: √580 × ∛510 ≈ 24 × 8 = 192.
Step 4: Approximate 49.999 as 50 and 3.999 as 4.
Step 5: Multiply: 49.999 × 3.999 ≈ 50 × 4 = 200.
Step 6: Add the two approximate parts: 192 + 200 = 392.
Step 7: Compare with the options: 392 is one of the given choices and matches the approximate value well.
Verification / Alternative check:
If we used a calculator, we would get a more precise value close to 392, confirming the correctness of this approximation strategy. Even if our approximations for the roots are slightly off, the final answer remains closest to 392 among the given options, because the other options (384, 410, 372, 360) are either significantly lower or higher than the reasonable estimated value.
Why Other Options Are Wrong:
384 and 372 are too low, given that the second term alone is already about 200 and the first term is clearly above 180.
410 and 360 are on the higher or much lower side compared to our careful estimate. None of these match the sum of 192 and 200 as closely as 392 does.
Common Pitfalls:
A major pitfall is over-approximating or under-approximating the roots or decimals without checking the effect on the total. Some students may approximate √580 as 23 or 25 incorrectly or mis-handle the cube root of 510. Always pick the nearest perfect square or cube to base your approximation, and remember to approximate all parts consistently.
Final Answer:
The approximate value of the expression is 392.
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