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Finding the Fourth Proportional to 259.89, 389.87 and 86.61

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Solution

The fourth proportional to 259.89, 389.87 and 86.61 is: 129.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.89 : 389.87 = 86.61 : x
  2. Step 2: Convert to fraction form
    259.89/389.87 = 86.61/x
  3. Step 3: Cross multiply
    259.89x = 389.87 × 86.61
  4. Step 4: Simplify right side
    259.89x = 33,766.64
  5. Step 5: Solve for x
    x = 33,766.64/259.89
  6. Step 6: Final answer
    x = 129.93

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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.