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Finding the Fourth Proportional to 260.83, 391.31 and 78.21

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Solution

The fourth proportional to 260.83, 391.31 and 78.21 is: 117.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.83 : 391.31 = 78.21 : x
  2. Step 2: Convert to fraction form
    260.83/391.31 = 78.21/x
  3. Step 3: Cross multiply
    260.83x = 391.31 × 78.21
  4. Step 4: Simplify right side
    260.83x = 30,604.36
  5. Step 5: Solve for x
    x = 30,604.36/260.83
  6. Step 6: Final answer
    x = 117.33

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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.