Time–decimal conversion: What decimal fraction of one hour is one second? (Choose the closest option to five decimal places.)
Aptitude
Decimal Fraction
Difficulty: Easy
Choose an option
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A.0025
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B.0256
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C.00027
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D.000126
Answer
Correct Answer: .00027
Explanation
Introduction / Context:Converting between time units and decimal fractions is common in data entry, time sheets, and physics problems. Here, we convert 1 second into the decimal part of one hour and then match to the nearest option provided.
Given Data / Assumptions:
- 1 hour = 60 minutes = 3600 seconds
- Quantity of interest: 1 second as a fraction of 1 hour
- Select the closest value among the options.
Concept / Approach:The decimal fraction of an hour represented by 1 second is 1/3600. Converting the fraction to a decimal ensures comparability with the choices. Since options are rounded, choose the closest to the true decimal value.
Step-by-Step Solution:
Fraction: 1 second / 1 hour = 1 / 3600Decimal: 1 / 3600 ≈ 0.000277777…To five decimal places, ≈ 0.00028 (exact rounding). Among the given options, the closest listed is 0.00027.Verification / Alternative check:
Check absolute difference: |0.00028 − 0.00027| = 0.00001, which is minimal compared with other options.Why Other Options Are Wrong:
- .0025 and .0256: Correspond to much larger fractions of an hour (minutes), not seconds.
- .000126: Too small (≈ 1/7937 hours), not equal to one second.
Common Pitfalls:
- Confusing 1/3600 with 1/3660 or 1/360.
- Misplacing the decimal point when converting small fractions.
Final Answer:
0.00027 (closest among options; true value ≈ 0.00028)