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Finding the Fourth Proportional to 638.78, 881.86 and 390.14

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Solution

The fourth proportional to 638.78, 881.86 and 390.14 is: 538.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.78 : 881.86 = 390.14 : x
  2. Step 2: Convert to fraction form
    638.78/881.86 = 390.14/x
  3. Step 3: Cross multiply
    638.78x = 881.86 × 390.14
  4. Step 4: Simplify right side
    638.78x = 344,048.86
  5. Step 5: Solve for x
    x = 344,048.86/638.78
  6. Step 6: Final answer
    x = 538.60

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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.