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Finding the Fourth Proportional to 103.72, 155.54 and 85.76

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Solution

The fourth proportional to 103.72, 155.54 and 85.76 is: 128.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.72 : 155.54 = 85.76 : x
  2. Step 2: Convert to fraction form
    103.72/155.54 = 85.76/x
  3. Step 3: Cross multiply
    103.72x = 155.54 × 85.76
  4. Step 4: Simplify right side
    103.72x = 13,339.11
  5. Step 5: Solve for x
    x = 13,339.11/103.72
  6. Step 6: Final answer
    x = 128.61

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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.