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Finding the Fourth Proportional to 256.78, 385.17 and 221.55

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Solution

The fourth proportional to 256.78, 385.17 and 221.55 is: 332.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.78 : 385.17 = 221.55 : x
  2. Step 2: Convert to fraction form
    256.78/385.17 = 221.55/x
  3. Step 3: Cross multiply
    256.78x = 385.17 × 221.55
  4. Step 4: Simplify right side
    256.78x = 85,334.41
  5. Step 5: Solve for x
    x = 85,334.41/256.78
  6. Step 6: Final answer
    x = 332.33

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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.