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Finding the Fourth Proportional to 19.90, 29.82 and 7.86

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Solution

The fourth proportional to 19.90, 29.82 and 7.86 is: 11.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.90 : 29.82 = 7.86 : x
  2. Step 2: Convert to fraction form
    19.90/29.82 = 7.86/x
  3. Step 3: Cross multiply
    19.90x = 29.82 × 7.86
  4. Step 4: Simplify right side
    19.90x = 234.39
  5. Step 5: Solve for x
    x = 234.39/19.90
  6. Step 6: Final answer
    x = 11.78

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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.