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Finding the Fourth Proportional to 422.70, 628.64 and 390.30

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Solution

The fourth proportional to 422.70, 628.64 and 390.30 is: 580.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    422.70 : 628.64 = 390.30 : x
  2. Step 2: Convert to fraction form
    422.70/628.64 = 390.30/x
  3. Step 3: Cross multiply
    422.70x = 628.64 × 390.30
  4. Step 4: Simplify right side
    422.70x = 245,356.24
  5. Step 5: Solve for x
    x = 245,356.24/422.70
  6. Step 6: Final answer
    x = 580.45

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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.