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Finding the Fourth Proportional to 20.54, 30.78 and 7.70

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Solution

The fourth proportional to 20.54, 30.78 and 7.70 is: 11.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.54 : 30.78 = 7.70 : x
  2. Step 2: Convert to fraction form
    20.54/30.78 = 7.70/x
  3. Step 3: Cross multiply
    20.54x = 30.78 × 7.70
  4. Step 4: Simplify right side
    20.54x = 236.85
  5. Step 5: Solve for x
    x = 236.85/20.54
  6. Step 6: Final answer
    x = 11.53

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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.