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Finding the Fourth Proportional to 80.72, 121.32 and 76.40

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Solution

The fourth proportional to 80.72, 121.32 and 76.40 is: 114.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.72 : 121.32 = 76.40 : x
  2. Step 2: Convert to fraction form
    80.72/121.32 = 76.40/x
  3. Step 3: Cross multiply
    80.72x = 121.32 × 76.40
  4. Step 4: Simplify right side
    80.72x = 9,268.85
  5. Step 5: Solve for x
    x = 9,268.85/80.72
  6. Step 6: Final answer
    x = 114.83

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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.