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Finding the Fourth Proportional to 103.80, 155.39 and 76.87

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Solution

The fourth proportional to 103.80, 155.39 and 76.87 is: 115.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.80 : 155.39 = 76.87 : x
  2. Step 2: Convert to fraction form
    103.80/155.39 = 76.87/x
  3. Step 3: Cross multiply
    103.80x = 155.39 × 76.87
  4. Step 4: Simplify right side
    103.80x = 11,944.63
  5. Step 5: Solve for x
    x = 11,944.63/103.80
  6. Step 6: Final answer
    x = 115.07

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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.