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Finding the Fourth Proportional to 431.85, 647.09 and 420.47

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Solution

The fourth proportional to 431.85, 647.09 and 420.47 is: 630.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.85 : 647.09 = 420.47 : x
  2. Step 2: Convert to fraction form
    431.85/647.09 = 420.47/x
  3. Step 3: Cross multiply
    431.85x = 647.09 × 420.47
  4. Step 4: Simplify right side
    431.85x = 272,076.59
  5. Step 5: Solve for x
    x = 272,076.59/431.85
  6. Step 6: Final answer
    x = 630.03

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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.