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Finding the Fourth Proportional to 20.55, 30.81 and 7.70

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Solution

The fourth proportional to 20.55, 30.81 and 7.70 is: 11.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.55 : 30.81 = 7.70 : x
  2. Step 2: Convert to fraction form
    20.55/30.81 = 7.70/x
  3. Step 3: Cross multiply
    20.55x = 30.81 × 7.70
  4. Step 4: Simplify right side
    20.55x = 237.20
  5. Step 5: Solve for x
    x = 237.20/20.55
  6. Step 6: Final answer
    x = 11.54

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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.