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Finding the Fourth Proportional to 77.91, 107.61 and 61.75

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Solution

The fourth proportional to 77.91, 107.61 and 61.75 is: 85.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.91 : 107.61 = 61.75 : x
  2. Step 2: Convert to fraction form
    77.91/107.61 = 61.75/x
  3. Step 3: Cross multiply
    77.91x = 107.61 × 61.75
  4. Step 4: Simplify right side
    77.91x = 6,644.07
  5. Step 5: Solve for x
    x = 6,644.07/77.91
  6. Step 6: Final answer
    x = 85.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.