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Finding the Fourth Proportional to 259.61, 389.49 and 86.28

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Solution

The fourth proportional to 259.61, 389.49 and 86.28 is: 129.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.61 : 389.49 = 86.28 : x
  2. Step 2: Convert to fraction form
    259.61/389.49 = 86.28/x
  3. Step 3: Cross multiply
    259.61x = 389.49 × 86.28
  4. Step 4: Simplify right side
    259.61x = 33,603.25
  5. Step 5: Solve for x
    x = 33,603.25/259.61
  6. Step 6: Final answer
    x = 129.44

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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.