Finding the Fourth Proportional to 139.83, 209.55 and 82.09

Step by Step Solution

1. Step 1: Write the proportion equation
   139.83 : 209.55 = 82.09 : x
2. Step 2: Convert to fraction form
   139.83/209.55 = 82.09/x
3. Step 3: Cross multiply
   139.83x = 209.55 × 82.09
4. Step 4: Simplify right side
   139.83x = 17,201.96
5. Step 5: Solve for x
   x = 17,201.96/139.83
6. Step 6: Final answer
   x = 123.02