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Finding the Fourth Proportional to 257.90, 355.90 and 139.87

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Solution

The fourth proportional to 257.90, 355.90 and 139.87 is: 193.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.90 : 355.90 = 139.87 : x
  2. Step 2: Convert to fraction form
    257.90/355.90 = 139.87/x
  3. Step 3: Cross multiply
    257.90x = 355.90 × 139.87
  4. Step 4: Simplify right side
    257.90x = 49,778.94
  5. Step 5: Solve for x
    x = 49,778.94/257.90
  6. Step 6: Final answer
    x = 193.02

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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.