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Finding the Fourth Proportional to 128.71, 192.45 and 112.61

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Solution

The fourth proportional to 128.71, 192.45 and 112.61 is: 168.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.71 : 192.45 = 112.61 : x
  2. Step 2: Convert to fraction form
    128.71/192.45 = 112.61/x
  3. Step 3: Cross multiply
    128.71x = 192.45 × 112.61
  4. Step 4: Simplify right side
    128.71x = 21,672.70
  5. Step 5: Solve for x
    x = 21,672.70/128.71
  6. Step 6: Final answer
    x = 168.38

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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.