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Finding the Fourth Proportional to 171.78, 257.12 and 128.37

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Solution

The fourth proportional to 171.78, 257.12 and 128.37 is: 192.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    171.78 : 257.12 = 128.37 : x
  2. Step 2: Convert to fraction form
    171.78/257.12 = 128.37/x
  3. Step 3: Cross multiply
    171.78x = 257.12 × 128.37
  4. Step 4: Simplify right side
    171.78x = 33,006.49
  5. Step 5: Solve for x
    x = 33,006.49/171.78
  6. Step 6: Final answer
    x = 192.14

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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.