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Finding the Fourth Proportional to 81.93, 122.67 and 78.15

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Solution

The fourth proportional to 81.93, 122.67 and 78.15 is: 117.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.93 : 122.67 = 78.15 : x
  2. Step 2: Convert to fraction form
    81.93/122.67 = 78.15/x
  3. Step 3: Cross multiply
    81.93x = 122.67 × 78.15
  4. Step 4: Simplify right side
    81.93x = 9,586.66
  5. Step 5: Solve for x
    x = 9,586.66/81.93
  6. Step 6: Final answer
    x = 117.01

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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.