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Finding the Fourth Proportional to 257.25, 385.94 and 86.25

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Solution

The fourth proportional to 257.25, 385.94 and 86.25 is: 129.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.25 : 385.94 = 86.25 : x
  2. Step 2: Convert to fraction form
    257.25/385.94 = 86.25/x
  3. Step 3: Cross multiply
    257.25x = 385.94 × 86.25
  4. Step 4: Simplify right side
    257.25x = 33,286.89
  5. Step 5: Solve for x
    x = 33,286.89/257.25
  6. Step 6: Final answer
    x = 129.40

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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.