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Finding the Fourth Proportional to 128.63, 192.78 and 79.73

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Solution

The fourth proportional to 128.63, 192.78 and 79.73 is: 119.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.63 : 192.78 = 79.73 : x
  2. Step 2: Convert to fraction form
    128.63/192.78 = 79.73/x
  3. Step 3: Cross multiply
    128.63x = 192.78 × 79.73
  4. Step 4: Simplify right side
    128.63x = 15,370.35
  5. Step 5: Solve for x
    x = 15,370.35/128.63
  6. Step 6: Final answer
    x = 119.49

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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.