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Finding the Fourth Proportional to 259.56, 389.21 and 86.17

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Solution

The fourth proportional to 259.56, 389.21 and 86.17 is: 129.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.56 : 389.21 = 86.17 : x
  2. Step 2: Convert to fraction form
    259.56/389.21 = 86.17/x
  3. Step 3: Cross multiply
    259.56x = 389.21 × 86.17
  4. Step 4: Simplify right side
    259.56x = 33,538.04
  5. Step 5: Solve for x
    x = 33,538.04/259.56
  6. Step 6: Final answer
    x = 129.21

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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.