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Finding the Fourth Proportional to 260.72, 391.15 and 78.12

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Solution

The fourth proportional to 260.72, 391.15 and 78.12 is: 117.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.72 : 391.15 = 78.12 : x
  2. Step 2: Convert to fraction form
    260.72/391.15 = 78.12/x
  3. Step 3: Cross multiply
    260.72x = 391.15 × 78.12
  4. Step 4: Simplify right side
    260.72x = 30,556.74
  5. Step 5: Solve for x
    x = 30,556.74/260.72
  6. Step 6: Final answer
    x = 117.20

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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.