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Finding the Fourth Proportional to 128.39, 192.38 and 47.18

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Solution

The fourth proportional to 128.39, 192.38 and 47.18 is: 70.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.39 : 192.38 = 47.18 : x
  2. Step 2: Convert to fraction form
    128.39/192.38 = 47.18/x
  3. Step 3: Cross multiply
    128.39x = 192.38 × 47.18
  4. Step 4: Simplify right side
    128.39x = 9,076.73
  5. Step 5: Solve for x
    x = 9,076.73/128.39
  6. Step 6: Final answer
    x = 70.70

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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.