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Finding the Fourth Proportional to 512.81, 768.87 and 421.28

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Solution

The fourth proportional to 512.81, 768.87 and 421.28 is: 631.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    512.81 : 768.87 = 421.28 : x
  2. Step 2: Convert to fraction form
    512.81/768.87 = 421.28/x
  3. Step 3: Cross multiply
    512.81x = 768.87 × 421.28
  4. Step 4: Simplify right side
    512.81x = 323,909.55
  5. Step 5: Solve for x
    x = 323,909.55/512.81
  6. Step 6: Final answer
    x = 631.64

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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.