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Finding the Fourth Proportional to 119.67, 165.11 and 78.21

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Solution

The fourth proportional to 119.67, 165.11 and 78.21 is: 107.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    119.67 : 165.11 = 78.21 : x
  2. Step 2: Convert to fraction form
    119.67/165.11 = 78.21/x
  3. Step 3: Cross multiply
    119.67x = 165.11 × 78.21
  4. Step 4: Simplify right side
    119.67x = 12,912.86
  5. Step 5: Solve for x
    x = 12,912.86/119.67
  6. Step 6: Final answer
    x = 107.90

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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.