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Finding the Fourth Proportional to 100.05, 138.23 and 78

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Solution

The fourth proportional to 100.05, 138.23 and 78 is: 107.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.05 : 138.23 = 78 : x
  2. Step 2: Convert to fraction form
    100.05/138.23 = 78/x
  3. Step 3: Cross multiply
    100.05x = 138.23 × 78
  4. Step 4: Simplify right side
    100.05x = 10,781.94
  5. Step 5: Solve for x
    x = 10,781.94/100.05
  6. Step 6: Final answer
    x = 107.77

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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.