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Finding the Fourth Proportional to 102.20, 140.86 and 77.60

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Solution

The fourth proportional to 102.20, 140.86 and 77.60 is: 106.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.20 : 140.86 = 77.60 : x
  2. Step 2: Convert to fraction form
    102.20/140.86 = 77.60/x
  3. Step 3: Cross multiply
    102.20x = 140.86 × 77.60
  4. Step 4: Simplify right side
    102.20x = 10,930.74
  5. Step 5: Solve for x
    x = 10,930.74/102.20
  6. Step 6: Final answer
    x = 106.95

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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.