Time–decimal conversion: What decimal fraction of one hour is one second? (Choose the closest option to five decimal places.)

Difficulty: Easy

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)

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