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Finding the Fourth Proportional to 721.08, 1,081.32 and 258.72

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Solution

The fourth proportional to 721.08, 1,081.32 and 258.72 is: 387.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.08 : 1,081.32 = 258.72 : x
  2. Step 2: Convert to fraction form
    721.08/1,081.32 = 258.72/x
  3. Step 3: Cross multiply
    721.08x = 1,081.32 × 258.72
  4. Step 4: Simplify right side
    721.08x = 279,759.11
  5. Step 5: Solve for x
    x = 279,759.11/721.08
  6. Step 6: Final answer
    x = 387.97

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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.