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Finding the Fourth Proportional to 128.61, 192.78 and 82.89

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Solution

The fourth proportional to 128.61, 192.78 and 82.89 is: 124.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.61 : 192.78 = 82.89 : x
  2. Step 2: Convert to fraction form
    128.61/192.78 = 82.89/x
  3. Step 3: Cross multiply
    128.61x = 192.78 × 82.89
  4. Step 4: Simplify right side
    128.61x = 15,979.53
  5. Step 5: Solve for x
    x = 15,979.53/128.61
  6. Step 6: Final answer
    x = 124.25

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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.