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Finding the Fourth Proportional to 42.20, 63.40 and 28.70

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Solution

The fourth proportional to 42.20, 63.40 and 28.70 is: 43.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.20 : 63.40 = 28.70 : x
  2. Step 2: Convert to fraction form
    42.20/63.40 = 28.70/x
  3. Step 3: Cross multiply
    42.20x = 63.40 × 28.70
  4. Step 4: Simplify right side
    42.20x = 1,819.58
  5. Step 5: Solve for x
    x = 1,819.58/42.20
  6. Step 6: Final answer
    x = 43.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.