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Finding the Fourth Proportional to 128.98, 192.35 and 121.79

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Solution

The fourth proportional to 128.98, 192.35 and 121.79 is: 181.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.98 : 192.35 = 121.79 : x
  2. Step 2: Convert to fraction form
    128.98/192.35 = 121.79/x
  3. Step 3: Cross multiply
    128.98x = 192.35 × 121.79
  4. Step 4: Simplify right side
    128.98x = 23,426.31
  5. Step 5: Solve for x
    x = 23,426.31/128.98
  6. Step 6: Final answer
    x = 181.63

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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.