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Finding the Fourth Proportional to 12.78, 19.20 and 9.78

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Solution

The fourth proportional to 12.78, 19.20 and 9.78 is: 14.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.78 : 19.20 = 9.78 : x
  2. Step 2: Convert to fraction form
    12.78/19.20 = 9.78/x
  3. Step 3: Cross multiply
    12.78x = 19.20 × 9.78
  4. Step 4: Simplify right side
    12.78x = 187.78
  5. Step 5: Solve for x
    x = 187.78/12.78
  6. Step 6: Final answer
    x = 14.69

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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.