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Finding the Fourth Proportional to 68.78, 103.18 and 20.69

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Solution

The fourth proportional to 68.78, 103.18 and 20.69 is: 31.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    68.78 : 103.18 = 20.69 : x
  2. Step 2: Convert to fraction form
    68.78/103.18 = 20.69/x
  3. Step 3: Cross multiply
    68.78x = 103.18 × 20.69
  4. Step 4: Simplify right side
    68.78x = 2,134.79
  5. Step 5: Solve for x
    x = 2,134.79/68.78
  6. Step 6: Final answer
    x = 31.04

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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.