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Finding the Fourth Proportional to 128.87, 193.12 and 87.69

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Solution

The fourth proportional to 128.87, 193.12 and 87.69 is: 131.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.87 : 193.12 = 87.69 : x
  2. Step 2: Convert to fraction form
    128.87/193.12 = 87.69/x
  3. Step 3: Cross multiply
    128.87x = 193.12 × 87.69
  4. Step 4: Simplify right side
    128.87x = 16,934.69
  5. Step 5: Solve for x
    x = 16,934.69/128.87
  6. Step 6: Final answer
    x = 131.41

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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.