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Finding the Fourth Proportional to 100.82, 139.13 and 90.87

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Solution

The fourth proportional to 100.82, 139.13 and 90.87 is: 125.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.82 : 139.13 = 90.87 : x
  2. Step 2: Convert to fraction form
    100.82/139.13 = 90.87/x
  3. Step 3: Cross multiply
    100.82x = 139.13 × 90.87
  4. Step 4: Simplify right side
    100.82x = 12,641.59
  5. Step 5: Solve for x
    x = 12,641.59/100.82
  6. Step 6: Final answer
    x = 125.39

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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.