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Finding the Fourth Proportional to 100.87, 139.25 and 87.77

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Solution

The fourth proportional to 100.87, 139.25 and 87.77 is: 121.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.87 : 139.25 = 87.77 : x
  2. Step 2: Convert to fraction form
    100.87/139.25 = 87.77/x
  3. Step 3: Cross multiply
    100.87x = 139.25 × 87.77
  4. Step 4: Simplify right side
    100.87x = 12,221.97
  5. Step 5: Solve for x
    x = 12,221.97/100.87
  6. Step 6: Final answer
    x = 121.17

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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.