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Finding the Fourth Proportional to 260.90, 391.34 and 78.30

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Solution

The fourth proportional to 260.90, 391.34 and 78.30 is: 117.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.90 : 391.34 = 78.30 : x
  2. Step 2: Convert to fraction form
    260.90/391.34 = 78.30/x
  3. Step 3: Cross multiply
    260.90x = 391.34 × 78.30
  4. Step 4: Simplify right side
    260.90x = 30,641.92
  5. Step 5: Solve for x
    x = 30,641.92/260.90
  6. Step 6: Final answer
    x = 117.45

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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.