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Finding the Fourth Proportional to 99.87, 137.85 and 72.39

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Solution

The fourth proportional to 99.87, 137.85 and 72.39 is: 99.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.87 : 137.85 = 72.39 : x
  2. Step 2: Convert to fraction form
    99.87/137.85 = 72.39/x
  3. Step 3: Cross multiply
    99.87x = 137.85 × 72.39
  4. Step 4: Simplify right side
    99.87x = 9,978.96
  5. Step 5: Solve for x
    x = 9,978.96/99.87
  6. Step 6: Final answer
    x = 99.92

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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.