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Finding the Fourth Proportional to 87.74, 120.90 and 77.82

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Solution

The fourth proportional to 87.74, 120.90 and 77.82 is: 107.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.74 : 120.90 = 77.82 : x
  2. Step 2: Convert to fraction form
    87.74/120.90 = 77.82/x
  3. Step 3: Cross multiply
    87.74x = 120.90 × 77.82
  4. Step 4: Simplify right side
    87.74x = 9,408.44
  5. Step 5: Solve for x
    x = 9,408.44/87.74
  6. Step 6: Final answer
    x = 107.23

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.