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Finding the Fourth Proportional to 721, 1,081.50 and 208

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Solution

The fourth proportional to 721, 1,081.50 and 208 is: 312

Step by Step Solution

  1. Step 1: Write the proportion equation
    721 : 1,081.50 = 208 : x
  2. Step 2: Convert to fraction form
    721/1,081.50 = 208/x
  3. Step 3: Cross multiply
    721x = 1,081.50 × 208
  4. Step 4: Simplify right side
    721x = 224,952
  5. Step 5: Solve for x
    x = 224,952/721
  6. Step 6: Final answer
    x = 312

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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.