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Finding the Fourth Proportional to 205.78, 308.72 and 84.05

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Solution

The fourth proportional to 205.78, 308.72 and 84.05 is: 126.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.78 : 308.72 = 84.05 : x
  2. Step 2: Convert to fraction form
    205.78/308.72 = 84.05/x
  3. Step 3: Cross multiply
    205.78x = 308.72 × 84.05
  4. Step 4: Simplify right side
    205.78x = 25,945.95
  5. Step 5: Solve for x
    x = 25,945.95/205.78
  6. Step 6: Final answer
    x = 126.09

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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.