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Finding the Fourth Proportional to 80.99, 120.78 and 76.20

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Solution

The fourth proportional to 80.99, 120.78 and 76.20 is: 113.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.99 : 120.78 = 76.20 : x
  2. Step 2: Convert to fraction form
    80.99/120.78 = 76.20/x
  3. Step 3: Cross multiply
    80.99x = 120.78 × 76.20
  4. Step 4: Simplify right side
    80.99x = 9,203.44
  5. Step 5: Solve for x
    x = 9,203.44/80.99
  6. Step 6: Final answer
    x = 113.63

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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.