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Finding the Fourth Proportional to 721.20, 1,081.86 and 259.08

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Solution

The fourth proportional to 721.20, 1,081.86 and 259.08 is: 388.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.20 : 1,081.86 = 259.08 : x
  2. Step 2: Convert to fraction form
    721.20/1,081.86 = 259.08/x
  3. Step 3: Cross multiply
    721.20x = 1,081.86 × 259.08
  4. Step 4: Simplify right side
    721.20x = 280,288.29
  5. Step 5: Solve for x
    x = 280,288.29/721.20
  6. Step 6: Final answer
    x = 388.64

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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.