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Finding the Fourth Proportional to 5.20, 7.81 and 3.87

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Solution

The fourth proportional to 5.20, 7.81 and 3.87 is: 5.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    5.20 : 7.81 = 3.87 : x
  2. Step 2: Convert to fraction form
    5.20/7.81 = 3.87/x
  3. Step 3: Cross multiply
    5.20x = 7.81 × 3.87
  4. Step 4: Simplify right side
    5.20x = 30.22
  5. Step 5: Solve for x
    x = 30.22/5.20
  6. Step 6: Final answer
    x = 5.81

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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.