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Finding the Fourth Proportional to 120.78, 181.09 and 71.92

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Solution

The fourth proportional to 120.78, 181.09 and 71.92 is: 107.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.78 : 181.09 = 71.92 : x
  2. Step 2: Convert to fraction form
    120.78/181.09 = 71.92/x
  3. Step 3: Cross multiply
    120.78x = 181.09 × 71.92
  4. Step 4: Simplify right side
    120.78x = 13,023.36
  5. Step 5: Solve for x
    x = 13,023.36/120.78
  6. Step 6: Final answer
    x = 107.82

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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.