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Finding the Fourth Proportional to 128.79, 192.96 and 56.61

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Solution

The fourth proportional to 128.79, 192.96 and 56.61 is: 84.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.79 : 192.96 = 56.61 : x
  2. Step 2: Convert to fraction form
    128.79/192.96 = 56.61/x
  3. Step 3: Cross multiply
    128.79x = 192.96 × 56.61
  4. Step 4: Simplify right side
    128.79x = 10,923.47
  5. Step 5: Solve for x
    x = 10,923.47/128.79
  6. Step 6: Final answer
    x = 84.82

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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.