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Finding the Fourth Proportional to 155.12, 213.84 and 128.79

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Solution

The fourth proportional to 155.12, 213.84 and 128.79 is: 177.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    155.12 : 213.84 = 128.79 : x
  2. Step 2: Convert to fraction form
    155.12/213.84 = 128.79/x
  3. Step 3: Cross multiply
    155.12x = 213.84 × 128.79
  4. Step 4: Simplify right side
    155.12x = 27,540.45
  5. Step 5: Solve for x
    x = 27,540.45/155.12
  6. Step 6: Final answer
    x = 177.55

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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.