Finding the Fourth Proportional to 139.82, 209.88 and 131.31

Step by Step Solution

1. Step 1: Write the proportion equation
   139.82 : 209.88 = 131.31 : x
2. Step 2: Convert to fraction form
   139.82/209.88 = 131.31/x
3. Step 3: Cross multiply
   139.82x = 209.88 × 131.31
4. Step 4: Simplify right side
   139.82x = 27,558.69
5. Step 5: Solve for x
   x = 27,558.69/139.82
6. Step 6: Final answer
   x = 197.11