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Finding the Fourth Proportional to 19.78, 29.66 and 7.75

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Solution

The fourth proportional to 19.78, 29.66 and 7.75 is: 11.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.78 : 29.66 = 7.75 : x
  2. Step 2: Convert to fraction form
    19.78/29.66 = 7.75/x
  3. Step 3: Cross multiply
    19.78x = 29.66 × 7.75
  4. Step 4: Simplify right side
    19.78x = 229.88
  5. Step 5: Solve for x
    x = 229.88/19.78
  6. Step 6: Final answer
    x = 11.62

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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.