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Finding the Fourth Proportional to 18.70, 28.05 and 8.55

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Solution

The fourth proportional to 18.70, 28.05 and 8.55 is: 12.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.70 : 28.05 = 8.55 : x
  2. Step 2: Convert to fraction form
    18.70/28.05 = 8.55/x
  3. Step 3: Cross multiply
    18.70x = 28.05 × 8.55
  4. Step 4: Simplify right side
    18.70x = 239.83
  5. Step 5: Solve for x
    x = 239.83/18.70
  6. Step 6: Final answer
    x = 12.83

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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.