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Finding the Fourth Proportional to 256.89, 385.46 and 128.64

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Solution

The fourth proportional to 256.89, 385.46 and 128.64 is: 193.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.89 : 385.46 = 128.64 : x
  2. Step 2: Convert to fraction form
    256.89/385.46 = 128.64/x
  3. Step 3: Cross multiply
    256.89x = 385.46 × 128.64
  4. Step 4: Simplify right side
    256.89x = 49,584.93
  5. Step 5: Solve for x
    x = 49,584.93/256.89
  6. Step 6: Final answer
    x = 193.02

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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.