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Finding the Fourth Proportional to 80.40, 120.32 and 78.09

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Solution

The fourth proportional to 80.40, 120.32 and 78.09 is: 116.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.40 : 120.32 = 78.09 : x
  2. Step 2: Convert to fraction form
    80.40/120.32 = 78.09/x
  3. Step 3: Cross multiply
    80.40x = 120.32 × 78.09
  4. Step 4: Simplify right side
    80.40x = 9,394.80
  5. Step 5: Solve for x
    x = 9,394.80/80.40
  6. Step 6: Final answer
    x = 116.86

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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.