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Finding the Fourth Proportional to 640.76, 961.12 and 256

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Solution

The fourth proportional to 640.76, 961.12 and 256 is: 383.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.76 : 961.12 = 256 : x
  2. Step 2: Convert to fraction form
    640.76/961.12 = 256/x
  3. Step 3: Cross multiply
    640.76x = 961.12 × 256
  4. Step 4: Simplify right side
    640.76x = 246,046.72
  5. Step 5: Solve for x
    x = 246,046.72/640.76
  6. Step 6: Final answer
    x = 383.99

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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.