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Finding the Fourth Proportional to 81.68, 122.69 and 78.94

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Solution

The fourth proportional to 81.68, 122.69 and 78.94 is: 118.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.68 : 122.69 = 78.94 : x
  2. Step 2: Convert to fraction form
    81.68/122.69 = 78.94/x
  3. Step 3: Cross multiply
    81.68x = 122.69 × 78.94
  4. Step 4: Simplify right side
    81.68x = 9,685.15
  5. Step 5: Solve for x
    x = 9,685.15/81.68
  6. Step 6: Final answer
    x = 118.57

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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.