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Finding the Fourth Proportional to 128.17, 191.41 and 121.15

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Solution

The fourth proportional to 128.17, 191.41 and 121.15 is: 180.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.17 : 191.41 = 121.15 : x
  2. Step 2: Convert to fraction form
    128.17/191.41 = 121.15/x
  3. Step 3: Cross multiply
    128.17x = 191.41 × 121.15
  4. Step 4: Simplify right side
    128.17x = 23,189.32
  5. Step 5: Solve for x
    x = 23,189.32/128.17
  6. Step 6: Final answer
    x = 180.93

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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.