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Finding the Fourth Proportional to 721.21, 1,081.70 and 258.98

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Solution

The fourth proportional to 721.21, 1,081.70 and 258.98 is: 388.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.21 : 1,081.70 = 258.98 : x
  2. Step 2: Convert to fraction form
    721.21/1,081.70 = 258.98/x
  3. Step 3: Cross multiply
    721.21x = 1,081.70 × 258.98
  4. Step 4: Simplify right side
    721.21x = 280,131.96
  5. Step 5: Solve for x
    x = 280,131.96/721.21
  6. Step 6: Final answer
    x = 388.42

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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.