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Finding the Fourth Proportional to 128.13, 190.83 and 121.11

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Solution

The fourth proportional to 128.13, 190.83 and 121.11 is: 180.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.13 : 190.83 = 121.11 : x
  2. Step 2: Convert to fraction form
    128.13/190.83 = 121.11/x
  3. Step 3: Cross multiply
    128.13x = 190.83 × 121.11
  4. Step 4: Simplify right side
    128.13x = 23,111.42
  5. Step 5: Solve for x
    x = 23,111.42/128.13
  6. Step 6: Final answer
    x = 180.37

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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.