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Finding the Fourth Proportional to 100.82, 139.09 and 77.47

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Solution

The fourth proportional to 100.82, 139.09 and 77.47 is: 106.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.82 : 139.09 = 77.47 : x
  2. Step 2: Convert to fraction form
    100.82/139.09 = 77.47/x
  3. Step 3: Cross multiply
    100.82x = 139.09 × 77.47
  4. Step 4: Simplify right side
    100.82x = 10,774.76
  5. Step 5: Solve for x
    x = 10,774.76/100.82
  6. Step 6: Final answer
    x = 106.87

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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.