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Finding the Fourth Proportional to 19.89, 29.86 and 7.88

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Solution

The fourth proportional to 19.89, 29.86 and 7.88 is: 11.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.89 : 29.86 = 7.88 : x
  2. Step 2: Convert to fraction form
    19.89/29.86 = 7.88/x
  3. Step 3: Cross multiply
    19.89x = 29.86 × 7.88
  4. Step 4: Simplify right side
    19.89x = 235.13
  5. Step 5: Solve for x
    x = 235.13/19.89
  6. Step 6: Final answer
    x = 11.82

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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.