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Finding the Fourth Proportional to 216.05, 298.17 and 128.72

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Solution

The fourth proportional to 216.05, 298.17 and 128.72 is: 177.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    216.05 : 298.17 = 128.72 : x
  2. Step 2: Convert to fraction form
    216.05/298.17 = 128.72/x
  3. Step 3: Cross multiply
    216.05x = 298.17 × 128.72
  4. Step 4: Simplify right side
    216.05x = 38,380.44
  5. Step 5: Solve for x
    x = 38,380.44/216.05
  6. Step 6: Final answer
    x = 177.65

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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.