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Finding the Fourth Proportional to 128.22, 190.98 and 121.20

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Solution

The fourth proportional to 128.22, 190.98 and 121.20 is: 180.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.22 : 190.98 = 121.20 : x
  2. Step 2: Convert to fraction form
    128.22/190.98 = 121.20/x
  3. Step 3: Cross multiply
    128.22x = 190.98 × 121.20
  4. Step 4: Simplify right side
    128.22x = 23,146.78
  5. Step 5: Solve for x
    x = 23,146.78/128.22
  6. Step 6: Final answer
    x = 180.52

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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.