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Finding the Fourth Proportional to 421.11, 630.78 and 392.63

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Solution

The fourth proportional to 421.11, 630.78 and 392.63 is: 588.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.11 : 630.78 = 392.63 : x
  2. Step 2: Convert to fraction form
    421.11/630.78 = 392.63/x
  3. Step 3: Cross multiply
    421.11x = 630.78 × 392.63
  4. Step 4: Simplify right side
    421.11x = 247,663.15
  5. Step 5: Solve for x
    x = 247,663.15/421.11
  6. Step 6: Final answer
    x = 588.12

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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.