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Finding the Fourth Proportional to 128.73, 191.98 and 121.55

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Solution

The fourth proportional to 128.73, 191.98 and 121.55 is: 181.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.73 : 191.98 = 121.55 : x
  2. Step 2: Convert to fraction form
    128.73/191.98 = 121.55/x
  3. Step 3: Cross multiply
    128.73x = 191.98 × 121.55
  4. Step 4: Simplify right side
    128.73x = 23,333.91
  5. Step 5: Solve for x
    x = 23,333.91/128.73
  6. Step 6: Final answer
    x = 181.26

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.