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Finding the Fourth Proportional to 427.20, 640.72 and 256

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Solution

The fourth proportional to 427.20, 640.72 and 256 is: 383.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.20 : 640.72 = 256 : x
  2. Step 2: Convert to fraction form
    427.20/640.72 = 256/x
  3. Step 3: Cross multiply
    427.20x = 640.72 × 256
  4. Step 4: Simplify right side
    427.20x = 164,024.32
  5. Step 5: Solve for x
    x = 164,024.32/427.20
  6. Step 6: Final answer
    x = 383.95

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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.