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Finding the Fourth Proportional to 128.46, 176.20 and 121.50

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Solution

The fourth proportional to 128.46, 176.20 and 121.50 is: 166.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.46 : 176.20 = 121.50 : x
  2. Step 2: Convert to fraction form
    128.46/176.20 = 121.50/x
  3. Step 3: Cross multiply
    128.46x = 176.20 × 121.50
  4. Step 4: Simplify right side
    128.46x = 21,408.30
  5. Step 5: Solve for x
    x = 21,408.30/128.46
  6. Step 6: Final answer
    x = 166.65

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.