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Finding the Fourth Proportional to 638.97, 882 and 390.21

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Solution

The fourth proportional to 638.97, 882 and 390.21 is: 538.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.97 : 882 = 390.21 : x
  2. Step 2: Convert to fraction form
    638.97/882 = 390.21/x
  3. Step 3: Cross multiply
    638.97x = 882 × 390.21
  4. Step 4: Simplify right side
    638.97x = 344,165.22
  5. Step 5: Solve for x
    x = 344,165.22/638.97
  6. Step 6: Final answer
    x = 538.63

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.