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Finding the Fourth Proportional to 20.76, 31.14 and 12.78

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Solution

The fourth proportional to 20.76, 31.14 and 12.78 is: 19.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.76 : 31.14 = 12.78 : x
  2. Step 2: Convert to fraction form
    20.76/31.14 = 12.78/x
  3. Step 3: Cross multiply
    20.76x = 31.14 × 12.78
  4. Step 4: Simplify right side
    20.76x = 397.97
  5. Step 5: Solve for x
    x = 397.97/20.76
  6. Step 6: Final answer
    x = 19.17

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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.