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Finding the Fourth Proportional to 70.78, 105.61 and 67.54

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Solution

The fourth proportional to 70.78, 105.61 and 67.54 is: 100.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.78 : 105.61 = 67.54 : x
  2. Step 2: Convert to fraction form
    70.78/105.61 = 67.54/x
  3. Step 3: Cross multiply
    70.78x = 105.61 × 67.54
  4. Step 4: Simplify right side
    70.78x = 7,132.90
  5. Step 5: Solve for x
    x = 7,132.90/70.78
  6. Step 6: Final answer
    x = 100.78

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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.