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Finding the Fourth Proportional to 639.26, 881.92 and 390.49

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Solution

The fourth proportional to 639.26, 881.92 and 390.49 is: 538.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.26 : 881.92 = 390.49 : x
  2. Step 2: Convert to fraction form
    639.26/881.92 = 390.49/x
  3. Step 3: Cross multiply
    639.26x = 881.92 × 390.49
  4. Step 4: Simplify right side
    639.26x = 344,380.94
  5. Step 5: Solve for x
    x = 344,380.94/639.26
  6. Step 6: Final answer
    x = 538.72

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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.