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Finding the Fourth Proportional to 19.85, 29.78 and 8.43

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Solution

The fourth proportional to 19.85, 29.78 and 8.43 is: 12.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.85 : 29.78 = 8.43 : x
  2. Step 2: Convert to fraction form
    19.85/29.78 = 8.43/x
  3. Step 3: Cross multiply
    19.85x = 29.78 × 8.43
  4. Step 4: Simplify right side
    19.85x = 251.00
  5. Step 5: Solve for x
    x = 251.00/19.85
  6. Step 6: Final answer
    x = 12.65

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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.