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Finding the Fourth Proportional to 260.80, 391.09 and 78.16

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Solution

The fourth proportional to 260.80, 391.09 and 78.16 is: 117.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.80 : 391.09 = 78.16 : x
  2. Step 2: Convert to fraction form
    260.80/391.09 = 78.16/x
  3. Step 3: Cross multiply
    260.80x = 391.09 × 78.16
  4. Step 4: Simplify right side
    260.80x = 30,568.40
  5. Step 5: Solve for x
    x = 30,568.40/260.80
  6. Step 6: Final answer
    x = 117.21

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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.