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Finding the Fourth Proportional to 639.18, 881.88 and 390.54

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Solution

The fourth proportional to 639.18, 881.88 and 390.54 is: 538.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.18 : 881.88 = 390.54 : x
  2. Step 2: Convert to fraction form
    639.18/881.88 = 390.54/x
  3. Step 3: Cross multiply
    639.18x = 881.88 × 390.54
  4. Step 4: Simplify right side
    639.18x = 344,409.42
  5. Step 5: Solve for x
    x = 344,409.42/639.18
  6. Step 6: Final answer
    x = 538.83

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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.