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Finding the Fourth Proportional to 81.07, 120.65 and 78.19

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Solution

The fourth proportional to 81.07, 120.65 and 78.19 is: 116.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.07 : 120.65 = 78.19 : x
  2. Step 2: Convert to fraction form
    81.07/120.65 = 78.19/x
  3. Step 3: Cross multiply
    81.07x = 120.65 × 78.19
  4. Step 4: Simplify right side
    81.07x = 9,433.62
  5. Step 5: Solve for x
    x = 9,433.62/81.07
  6. Step 6: Final answer
    x = 116.36

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.