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Finding the Fourth Proportional to 78.31, 108.54 and 76.87

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Solution

The fourth proportional to 78.31, 108.54 and 76.87 is: 106.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.31 : 108.54 = 76.87 : x
  2. Step 2: Convert to fraction form
    78.31/108.54 = 76.87/x
  3. Step 3: Cross multiply
    78.31x = 108.54 × 76.87
  4. Step 4: Simplify right side
    78.31x = 8,343.47
  5. Step 5: Solve for x
    x = 8,343.47/78.31
  6. Step 6: Final answer
    x = 106.54

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.