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Finding the Fourth Proportional to 257.12, 385.68 and 86.16

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Solution

The fourth proportional to 257.12, 385.68 and 86.16 is: 129.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.12 : 385.68 = 86.16 : x
  2. Step 2: Convert to fraction form
    257.12/385.68 = 86.16/x
  3. Step 3: Cross multiply
    257.12x = 385.68 × 86.16
  4. Step 4: Simplify right side
    257.12x = 33,230.19
  5. Step 5: Solve for x
    x = 33,230.19/257.12
  6. Step 6: Final answer
    x = 129.24

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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.