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Finding the Fourth Proportional to 120.54, 180.90 and 85.83

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Solution

The fourth proportional to 120.54, 180.90 and 85.83 is: 128.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.54 : 180.90 = 85.83 : x
  2. Step 2: Convert to fraction form
    120.54/180.90 = 85.83/x
  3. Step 3: Cross multiply
    120.54x = 180.90 × 85.83
  4. Step 4: Simplify right side
    120.54x = 15,526.65
  5. Step 5: Solve for x
    x = 15,526.65/120.54
  6. Step 6: Final answer
    x = 128.81

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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.