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Finding the Fourth Proportional to 257.12, 385.44 and 86

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Solution

The fourth proportional to 257.12, 385.44 and 86 is: 128.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.12 : 385.44 = 86 : x
  2. Step 2: Convert to fraction form
    257.12/385.44 = 86/x
  3. Step 3: Cross multiply
    257.12x = 385.44 × 86
  4. Step 4: Simplify right side
    257.12x = 33,147.84
  5. Step 5: Solve for x
    x = 33,147.84/257.12
  6. Step 6: Final answer
    x = 128.92

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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.