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Finding the Fourth Proportional to 72.40, 108.72 and 39.88

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Solution

The fourth proportional to 72.40, 108.72 and 39.88 is: 59.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.40 : 108.72 = 39.88 : x
  2. Step 2: Convert to fraction form
    72.40/108.72 = 39.88/x
  3. Step 3: Cross multiply
    72.40x = 108.72 × 39.88
  4. Step 4: Simplify right side
    72.40x = 4,335.75
  5. Step 5: Solve for x
    x = 4,335.75/72.40
  6. Step 6: Final answer
    x = 59.89

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.