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Finding the Fourth Proportional to 258.20, 387.31 and 113.90

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Solution

The fourth proportional to 258.20, 387.31 and 113.90 is: 170.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.20 : 387.31 = 113.90 : x
  2. Step 2: Convert to fraction form
    258.20/387.31 = 113.90/x
  3. Step 3: Cross multiply
    258.20x = 387.31 × 113.90
  4. Step 4: Simplify right side
    258.20x = 44,112.39
  5. Step 5: Solve for x
    x = 44,112.39/258.20
  6. Step 6: Final answer
    x = 170.85

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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.