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Finding the Fourth Proportional to 63.15, 87.11 and 39.86

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Solution

The fourth proportional to 63.15, 87.11 and 39.86 is: 54.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    63.15 : 87.11 = 39.86 : x
  2. Step 2: Convert to fraction form
    63.15/87.11 = 39.86/x
  3. Step 3: Cross multiply
    63.15x = 87.11 × 39.86
  4. Step 4: Simplify right side
    63.15x = 3,472.20
  5. Step 5: Solve for x
    x = 3,472.20/63.15
  6. Step 6: Final answer
    x = 54.98

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.