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Finding the Fourth Proportional to 85.35, 128.18 and 69.15

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Solution

The fourth proportional to 85.35, 128.18 and 69.15 is: 103.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.35 : 128.18 = 69.15 : x
  2. Step 2: Convert to fraction form
    85.35/128.18 = 69.15/x
  3. Step 3: Cross multiply
    85.35x = 128.18 × 69.15
  4. Step 4: Simplify right side
    85.35x = 8,864.30
  5. Step 5: Solve for x
    x = 8,864.30/85.35
  6. Step 6: Final answer
    x = 103.85

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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.