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Finding the Fourth Proportional to 80.78, 120.87 and 51.89

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Solution

The fourth proportional to 80.78, 120.87 and 51.89 is: 77.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.78 : 120.87 = 51.89 : x
  2. Step 2: Convert to fraction form
    80.78/120.87 = 51.89/x
  3. Step 3: Cross multiply
    80.78x = 120.87 × 51.89
  4. Step 4: Simplify right side
    80.78x = 6,271.34
  5. Step 5: Solve for x
    x = 6,271.34/80.78
  6. Step 6: Final answer
    x = 77.64

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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.