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Finding the Fourth Proportional to 422.13, 629.75 and 390.70

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Solution

The fourth proportional to 422.13, 629.75 and 390.70 is: 582.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    422.13 : 629.75 = 390.70 : x
  2. Step 2: Convert to fraction form
    422.13/629.75 = 390.70/x
  3. Step 3: Cross multiply
    422.13x = 629.75 × 390.70
  4. Step 4: Simplify right side
    422.13x = 246,043.33
  5. Step 5: Solve for x
    x = 246,043.33/422.13
  6. Step 6: Final answer
    x = 582.86

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.