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Finding the Fourth Proportional to 256.96, 385.32 and 128.56

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Solution

The fourth proportional to 256.96, 385.32 and 128.56 is: 192.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.96 : 385.32 = 128.56 : x
  2. Step 2: Convert to fraction form
    256.96/385.32 = 128.56/x
  3. Step 3: Cross multiply
    256.96x = 385.32 × 128.56
  4. Step 4: Simplify right side
    256.96x = 49,536.74
  5. Step 5: Solve for x
    x = 49,536.74/256.96
  6. Step 6: Final answer
    x = 192.78

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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.