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Finding the Fourth Proportional to 80.78, 110.78 and 76.70

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Solution

The fourth proportional to 80.78, 110.78 and 76.70 is: 105.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.78 : 110.78 = 76.70 : x
  2. Step 2: Convert to fraction form
    80.78/110.78 = 76.70/x
  3. Step 3: Cross multiply
    80.78x = 110.78 × 76.70
  4. Step 4: Simplify right side
    80.78x = 8,496.83
  5. Step 5: Solve for x
    x = 8,496.83/80.78
  6. Step 6: Final answer
    x = 105.18

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.