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Finding the Fourth Proportional to 102.90, 154.31 and 38.78

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Solution

The fourth proportional to 102.90, 154.31 and 38.78 is: 58.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.90 : 154.31 = 38.78 : x
  2. Step 2: Convert to fraction form
    102.90/154.31 = 38.78/x
  3. Step 3: Cross multiply
    102.90x = 154.31 × 38.78
  4. Step 4: Simplify right side
    102.90x = 5,984.14
  5. Step 5: Solve for x
    x = 5,984.14/102.90
  6. Step 6: Final answer
    x = 58.15

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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.