A recipe requires 1.25 liters of milk. You have 750 milliliters of milk. How many liters more milk do you...

1. TRANSLATE the problem information

• Given information:
  • Recipe requires: \(1.25\) liters of milk
  • Currently have: \(750\) milliliters of milk
  • Conversion factor: \(1\) liter \(= 1,000\) milliliters
  • Need to find: How many more liters of milk needed

• The key insight: We need to work in the same units to compare amounts

2. TRANSLATE units to work consistently

• Convert \(750\) milliliters to liters:

\(750 \mathrm{mL} \div 1,000 \mathrm{mL/L} = 0.75 \mathrm{L}\)

• Now we have everything in liters:

• Need: \(1.25\) L
• Have: \(0.75\) L

3. SIMPLIFY to find the difference

• Additional milk needed = What we need - What we have

• Additional milk = \(1.25 \mathrm{L} - 0.75 \mathrm{L} = 0.50 \mathrm{L}\)

Answer: B (0.50)

Why Students Usually Falter on This Problem

Most Common Error Path:

Weak TRANSLATE skill: Students convert units correctly but then select \(0.75\) L as their final answer without completing the subtraction step.

They correctly figure out that \(750 \mathrm{mL} = 0.75 \mathrm{L}\), see this value among the answer choices, and think "That's my answer!" without realizing they still need to calculate how much additional milk is required.

This may lead them to select Choice C (0.75)

Second Most Common Error:

Poor TRANSLATE reasoning: Students subtract in the wrong direction, calculating \(0.75 \mathrm{L} - 1.25 \mathrm{L} = -0.50 \mathrm{L}\), then get confused about the negative result.

Some might take the absolute value and still get \(0.50\) L (accidentally correct), while others get stuck on the negative number and abandon their systematic approach.

This leads to confusion and guessing among the remaining choices.

The Bottom Line:

This problem requires careful attention to what the question is actually asking for - not just unit conversion, but the difference between what's needed and what's available. Students who rush through often stop after the conversion step.