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Finding the Fourth Proportional to 128.73, 176.70 and 121.90

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Solution

The fourth proportional to 128.73, 176.70 and 121.90 is: 167.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.73 : 176.70 = 121.90 : x
  2. Step 2: Convert to fraction form
    128.73/176.70 = 121.90/x
  3. Step 3: Cross multiply
    128.73x = 176.70 × 121.90
  4. Step 4: Simplify right side
    128.73x = 21,539.73
  5. Step 5: Solve for x
    x = 21,539.73/128.73
  6. Step 6: Final answer
    x = 167.32

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.