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Finding the Fourth Proportional to 259.72, 389.54 and 86.39

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Solution

The fourth proportional to 259.72, 389.54 and 86.39 is: 129.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.72 : 389.54 = 86.39 : x
  2. Step 2: Convert to fraction form
    259.72/389.54 = 86.39/x
  3. Step 3: Cross multiply
    259.72x = 389.54 × 86.39
  4. Step 4: Simplify right side
    259.72x = 33,652.36
  5. Step 5: Solve for x
    x = 33,652.36/259.72
  6. Step 6: Final answer
    x = 129.57

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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.