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Finding the Fourth Proportional to 139.83, 209.75 and 128.09

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Solution

The fourth proportional to 139.83, 209.75 and 128.09 is: 192.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.83 : 209.75 = 128.09 : x
  2. Step 2: Convert to fraction form
    139.83/209.75 = 128.09/x
  3. Step 3: Cross multiply
    139.83x = 209.75 × 128.09
  4. Step 4: Simplify right side
    139.83x = 26,865.19
  5. Step 5: Solve for x
    x = 26,865.19/139.83
  6. Step 6: Final answer
    x = 192.13

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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.