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Finding the Fourth Proportional to 19.78, 29.72 and 12.17

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Solution

The fourth proportional to 19.78, 29.72 and 12.17 is: 18.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.78 : 29.72 = 12.17 : x
  2. Step 2: Convert to fraction form
    19.78/29.72 = 12.17/x
  3. Step 3: Cross multiply
    19.78x = 29.72 × 12.17
  4. Step 4: Simplify right side
    19.78x = 361.56
  5. Step 5: Solve for x
    x = 361.56/19.78
  6. Step 6: Final answer
    x = 18.28

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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.