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Finding the Fourth Proportional to 109.14, 163.28 and 78.78

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Solution

The fourth proportional to 109.14, 163.28 and 78.78 is: 117.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.14 : 163.28 = 78.78 : x
  2. Step 2: Convert to fraction form
    109.14/163.28 = 78.78/x
  3. Step 3: Cross multiply
    109.14x = 163.28 × 78.78
  4. Step 4: Simplify right side
    109.14x = 12,863.20
  5. Step 5: Solve for x
    x = 12,863.20/109.14
  6. Step 6: Final answer
    x = 117.86

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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.