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Finding the Fourth Proportional to 639.15, 881.87 and 390.38

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Solution

The fourth proportional to 639.15, 881.87 and 390.38 is: 538.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.15 : 881.87 = 390.38 : x
  2. Step 2: Convert to fraction form
    639.15/881.87 = 390.38/x
  3. Step 3: Cross multiply
    639.15x = 881.87 × 390.38
  4. Step 4: Simplify right side
    639.15x = 344,262.46
  5. Step 5: Solve for x
    x = 344,262.46/639.15
  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.