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Finding the Fourth Proportional to 99.20, 136.78 and 74.58

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Solution

The fourth proportional to 99.20, 136.78 and 74.58 is: 102.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.20 : 136.78 = 74.58 : x
  2. Step 2: Convert to fraction form
    99.20/136.78 = 74.58/x
  3. Step 3: Cross multiply
    99.20x = 136.78 × 74.58
  4. Step 4: Simplify right side
    99.20x = 10,201.05
  5. Step 5: Solve for x
    x = 10,201.05/99.20
  6. Step 6: Final answer
    x = 102.83

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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.