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Finding the Fourth Proportional to 78.62, 117.31 and 69.92

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Solution

The fourth proportional to 78.62, 117.31 and 69.92 is: 104.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.62 : 117.31 = 69.92 : x
  2. Step 2: Convert to fraction form
    78.62/117.31 = 69.92/x
  3. Step 3: Cross multiply
    78.62x = 117.31 × 69.92
  4. Step 4: Simplify right side
    78.62x = 8,201.55
  5. Step 5: Solve for x
    x = 8,201.55/78.62
  6. Step 6: Final answer
    x = 104.32

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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.