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Finding the Fourth Proportional to 256.96, 385.44 and 86.08

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Solution

The fourth proportional to 256.96, 385.44 and 86.08 is: 129.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.96 : 385.44 = 86.08 : x
  2. Step 2: Convert to fraction form
    256.96/385.44 = 86.08/x
  3. Step 3: Cross multiply
    256.96x = 385.44 × 86.08
  4. Step 4: Simplify right side
    256.96x = 33,178.68
  5. Step 5: Solve for x
    x = 33,178.68/256.96
  6. Step 6: Final answer
    x = 129.12

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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.