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Finding the Fourth Proportional to 422.90, 639.14 and 415.71

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Solution

The fourth proportional to 422.90, 639.14 and 415.71 is: 628.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    422.90 : 639.14 = 415.71 : x
  2. Step 2: Convert to fraction form
    422.90/639.14 = 415.71/x
  3. Step 3: Cross multiply
    422.90x = 639.14 × 415.71
  4. Step 4: Simplify right side
    422.90x = 265,694.81
  5. Step 5: Solve for x
    x = 265,694.81/422.90
  6. Step 6: Final answer
    x = 628.27

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.