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Finding the Fourth Proportional to 140.78, 212.05 and 128.02

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Solution

The fourth proportional to 140.78, 212.05 and 128.02 is: 192.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    140.78 : 212.05 = 128.02 : x
  2. Step 2: Convert to fraction form
    140.78/212.05 = 128.02/x
  3. Step 3: Cross multiply
    140.78x = 212.05 × 128.02
  4. Step 4: Simplify right side
    140.78x = 27,144.94
  5. Step 5: Solve for x
    x = 27,144.94/140.78
  6. Step 6: Final answer
    x = 192.83

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.