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Finding the Fourth Proportional to 77.91, 116.87 and 20.91

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Solution

The fourth proportional to 77.91, 116.87 and 20.91 is: 31.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.91 : 116.87 = 20.91 : x
  2. Step 2: Convert to fraction form
    77.91/116.87 = 20.91/x
  3. Step 3: Cross multiply
    77.91x = 116.87 × 20.91
  4. Step 4: Simplify right side
    77.91x = 2,443.65
  5. Step 5: Solve for x
    x = 2,443.65/77.91
  6. Step 6: Final answer
    x = 31.37

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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.