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Finding the Fourth Proportional to 27.70, 38.20 and 20.78

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Solution

The fourth proportional to 27.70, 38.20 and 20.78 is: 28.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    27.70 : 38.20 = 20.78 : x
  2. Step 2: Convert to fraction form
    27.70/38.20 = 20.78/x
  3. Step 3: Cross multiply
    27.70x = 38.20 × 20.78
  4. Step 4: Simplify right side
    27.70x = 793.80
  5. Step 5: Solve for x
    x = 793.80/27.70
  6. Step 6: Final answer
    x = 28.66

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.