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Finding the Fourth Proportional to 638.91, 879.51 and 498.78

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Solution

The fourth proportional to 638.91, 879.51 and 498.78 is: 686.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.91 : 879.51 = 498.78 : x
  2. Step 2: Convert to fraction form
    638.91/879.51 = 498.78/x
  3. Step 3: Cross multiply
    638.91x = 879.51 × 498.78
  4. Step 4: Simplify right side
    638.91x = 438,682.00
  5. Step 5: Solve for x
    x = 438,682.00/638.91
  6. Step 6: Final answer
    x = 686.61

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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.