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Finding the Fourth Proportional to 256.54, 384.90 and 128.20

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Solution

The fourth proportional to 256.54, 384.90 and 128.20 is: 192.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.54 : 384.90 = 128.20 : x
  2. Step 2: Convert to fraction form
    256.54/384.90 = 128.20/x
  3. Step 3: Cross multiply
    256.54x = 384.90 × 128.20
  4. Step 4: Simplify right side
    256.54x = 49,344.18
  5. Step 5: Solve for x
    x = 49,344.18/256.54
  6. Step 6: Final answer
    x = 192.34

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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.