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Finding the Fourth Proportional to 9.21, 13.81 and 7.87

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Solution

The fourth proportional to 9.21, 13.81 and 7.87 is: 11.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    9.21 : 13.81 = 7.87 : x
  2. Step 2: Convert to fraction form
    9.21/13.81 = 7.87/x
  3. Step 3: Cross multiply
    9.21x = 13.81 × 7.87
  4. Step 4: Simplify right side
    9.21x = 108.68
  5. Step 5: Solve for x
    x = 108.68/9.21
  6. Step 6: Final answer
    x = 11.80

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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.