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Finding the Fourth Proportional to 205.98, 308.71 and 84.21

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Solution

The fourth proportional to 205.98, 308.71 and 84.21 is: 126.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.98 : 308.71 = 84.21 : x
  2. Step 2: Convert to fraction form
    205.98/308.71 = 84.21/x
  3. Step 3: Cross multiply
    205.98x = 308.71 × 84.21
  4. Step 4: Simplify right side
    205.98x = 25,996.47
  5. Step 5: Solve for x
    x = 25,996.47/205.98
  6. Step 6: Final answer
    x = 126.21

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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.