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Finding the Fourth Proportional to 205.78, 284.01 and 128.20

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Solution

The fourth proportional to 205.78, 284.01 and 128.20 is: 176.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    205.78 : 284.01 = 128.20 : x
  2. Step 2: Convert to fraction form
    205.78/284.01 = 128.20/x
  3. Step 3: Cross multiply
    205.78x = 284.01 × 128.20
  4. Step 4: Simplify right side
    205.78x = 36,410.08
  5. Step 5: Solve for x
    x = 36,410.08/205.78
  6. Step 6: Final answer
    x = 176.94

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.