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Finding the Fourth Proportional to 81.15, 121.77 and 53.97

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Solution

The fourth proportional to 81.15, 121.77 and 53.97 is: 80.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.15 : 121.77 = 53.97 : x
  2. Step 2: Convert to fraction form
    81.15/121.77 = 53.97/x
  3. Step 3: Cross multiply
    81.15x = 121.77 × 53.97
  4. Step 4: Simplify right side
    81.15x = 6,571.93
  5. Step 5: Solve for x
    x = 6,571.93/81.15
  6. Step 6: Final answer
    x = 80.98

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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.