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Finding the Fourth Proportional to 259.28, 388.90 and 85.89

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Solution

The fourth proportional to 259.28, 388.90 and 85.89 is: 128.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.28 : 388.90 = 85.89 : x
  2. Step 2: Convert to fraction form
    259.28/388.90 = 85.89/x
  3. Step 3: Cross multiply
    259.28x = 388.90 × 85.89
  4. Step 4: Simplify right side
    259.28x = 33,404.65
  5. Step 5: Solve for x
    x = 33,404.65/259.28
  6. Step 6: Final answer
    x = 128.83

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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.