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Finding the Fourth Proportional to 100.20, 138.30 and 61.38

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Solution

The fourth proportional to 100.20, 138.30 and 61.38 is: 84.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.20 : 138.30 = 61.38 : x
  2. Step 2: Convert to fraction form
    100.20/138.30 = 61.38/x
  3. Step 3: Cross multiply
    100.20x = 138.30 × 61.38
  4. Step 4: Simplify right side
    100.20x = 8,488.85
  5. Step 5: Solve for x
    x = 8,488.85/100.20
  6. Step 6: Final answer
    x = 84.72

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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.