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Finding the Fourth Proportional to 128.76, 193.13 and 42.09

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Solution

The fourth proportional to 128.76, 193.13 and 42.09 is: 63.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.76 : 193.13 = 42.09 : x
  2. Step 2: Convert to fraction form
    128.76/193.13 = 42.09/x
  3. Step 3: Cross multiply
    128.76x = 193.13 × 42.09
  4. Step 4: Simplify right side
    128.76x = 8,129.12
  5. Step 5: Solve for x
    x = 8,129.12/128.76
  6. Step 6: Final answer
    x = 63.13

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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.