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Finding the Fourth Proportional to 100.62, 138.94 and 78.74

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Solution

The fourth proportional to 100.62, 138.94 and 78.74 is: 108.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.62 : 138.94 = 78.74 : x
  2. Step 2: Convert to fraction form
    100.62/138.94 = 78.74/x
  3. Step 3: Cross multiply
    100.62x = 138.94 × 78.74
  4. Step 4: Simplify right side
    100.62x = 10,940.14
  5. Step 5: Solve for x
    x = 10,940.14/100.62
  6. Step 6: Final answer
    x = 108.73

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.