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Finding the Fourth Proportional to 136.78, 204.90 and 85.30

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Solution

The fourth proportional to 136.78, 204.90 and 85.30 is: 127.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.78 : 204.90 = 85.30 : x
  2. Step 2: Convert to fraction form
    136.78/204.90 = 85.30/x
  3. Step 3: Cross multiply
    136.78x = 204.90 × 85.30
  4. Step 4: Simplify right side
    136.78x = 17,477.97
  5. Step 5: Solve for x
    x = 17,477.97/136.78
  6. Step 6: Final answer
    x = 127.78

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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.