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Finding the Fourth Proportional to 128.20, 192.30 and 121.60

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Solution

The fourth proportional to 128.20, 192.30 and 121.60 is: 182.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.20 : 192.30 = 121.60 : x
  2. Step 2: Convert to fraction form
    128.20/192.30 = 121.60/x
  3. Step 3: Cross multiply
    128.20x = 192.30 × 121.60
  4. Step 4: Simplify right side
    128.20x = 23,383.68
  5. Step 5: Solve for x
    x = 23,383.68/128.20
  6. Step 6: Final answer
    x = 182.40

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.