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Finding the Fourth Proportional to 69.78, 105.08 and 51.87

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Solution

The fourth proportional to 69.78, 105.08 and 51.87 is: 78.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    69.78 : 105.08 = 51.87 : x
  2. Step 2: Convert to fraction form
    69.78/105.08 = 51.87/x
  3. Step 3: Cross multiply
    69.78x = 105.08 × 51.87
  4. Step 4: Simplify right side
    69.78x = 5,450.24
  5. Step 5: Solve for x
    x = 5,450.24/69.78
  6. Step 6: Final answer
    x = 78.11

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.