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Finding the Fourth Proportional to 80.72, 120.72 and 77

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Solution

The fourth proportional to 80.72, 120.72 and 77 is: 115.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.72 : 120.72 = 77 : x
  2. Step 2: Convert to fraction form
    80.72/120.72 = 77/x
  3. Step 3: Cross multiply
    80.72x = 120.72 × 77
  4. Step 4: Simplify right side
    80.72x = 9,295.44
  5. Step 5: Solve for x
    x = 9,295.44/80.72
  6. Step 6: Final answer
    x = 115.16

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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.