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Finding the Fourth Proportional to 721.19, 1,081.79 and 208.19

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Solution

The fourth proportional to 721.19, 1,081.79 and 208.19 is: 312.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.19 : 1,081.79 = 208.19 : x
  2. Step 2: Convert to fraction form
    721.19/1,081.79 = 208.19/x
  3. Step 3: Cross multiply
    721.19x = 1,081.79 × 208.19
  4. Step 4: Simplify right side
    721.19x = 225,217.86
  5. Step 5: Solve for x
    x = 225,217.86/721.19
  6. Step 6: Final answer
    x = 312.29

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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.