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Finding the Fourth Proportional to 3.87, 5.31 and 3.80

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Solution

The fourth proportional to 3.87, 5.31 and 3.80 is: 5.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    3.87 : 5.31 = 3.80 : x
  2. Step 2: Convert to fraction form
    3.87/5.31 = 3.80/x
  3. Step 3: Cross multiply
    3.87x = 5.31 × 3.80
  4. Step 4: Simplify right side
    3.87x = 20.15
  5. Step 5: Solve for x
    x = 20.15/3.87
  6. Step 6: Final answer
    x = 5.21

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.