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Finding the Fourth Proportional to 80.65, 120.15 and 76.78

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Solution

The fourth proportional to 80.65, 120.15 and 76.78 is: 114.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.65 : 120.15 = 76.78 : x
  2. Step 2: Convert to fraction form
    80.65/120.15 = 76.78/x
  3. Step 3: Cross multiply
    80.65x = 120.15 × 76.78
  4. Step 4: Simplify right side
    80.65x = 9,224.90
  5. Step 5: Solve for x
    x = 9,224.90/80.65
  6. Step 6: Final answer
    x = 114.38

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.