Lani spent 15% of her 8-hour workday in meetings. How many minutes of her workday did she spend in meetings?

1. TRANSLATE the problem information

• Given information:
  • Lani's workday: 8 hours
  • Time in meetings: \(15\%\) of her workday
  • Find: How many minutes in meetings
• The question asks for the final answer in minutes, not hours

2. INFER the solution approach

• Since we need minutes but have hours, we must convert to minutes first
• Then calculate what \(15\%\) of that total represents
• This is a two-step process: convert units, then find percentage

3. SIMPLIFY by converting hours to minutes

• Total workday in minutes: \(8\) hours \(\times\) \(60\) minutes/hour \(= 480\) minutes

4. SIMPLIFY by calculating the percentage

• \(15\% = 0.15\) (convert percentage to decimal)
• Time in meetings: \(0.15 \times 480 = 72\) minutes

Answer: D. 72

Why Students Usually Falter on This Problem

Most Common Error Path:

Weak INFER skill: Students calculate \(15\%\) of 8 directly without converting to minutes first.

They compute \(0.15 \times 8 = 1.2\) and select that as their answer, not recognizing that 1.2 represents hours, not the required minutes. This leads them to select Choice A (1.2).

Second Most Common Error:

Poor SIMPLIFY execution: Students understand they need to convert to minutes and find a percentage, but make arithmetic errors in their calculations.

Common calculation mistakes include multiplying incorrectly (\(8 \times 60\) or \(0.15 \times 480\)) or confusing which operations to perform. This may lead them to select Choice C (48).

The Bottom Line:

This problem tests whether students can work with different units in percentage problems. The key insight is recognizing that when the question asks for a specific unit (minutes), all calculations must be done in that unit, even if the given information uses different units (hours).