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Finding the Fourth Proportional to 206.78, 309.92 and 85.01

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Solution

The fourth proportional to 206.78, 309.92 and 85.01 is: 127.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.78 : 309.92 = 85.01 : x
  2. Step 2: Convert to fraction form
    206.78/309.92 = 85.01/x
  3. Step 3: Cross multiply
    206.78x = 309.92 × 85.01
  4. Step 4: Simplify right side
    206.78x = 26,344.32
  5. Step 5: Solve for x
    x = 26,344.32/206.78
  6. Step 6: Final answer
    x = 127.41

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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.