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Finding the Fourth Proportional to 260.76, 391.20 and 78.18

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Solution

The fourth proportional to 260.76, 391.20 and 78.18 is: 117.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.76 : 391.20 = 78.18 : x
  2. Step 2: Convert to fraction form
    260.76/391.20 = 78.18/x
  3. Step 3: Cross multiply
    260.76x = 391.20 × 78.18
  4. Step 4: Simplify right side
    260.76x = 30,584.02
  5. Step 5: Solve for x
    x = 30,584.02/260.76
  6. Step 6: Final answer
    x = 117.29

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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.