Finding the Fourth Proportional to 139.58, 192.81 and 111.91

Step by Step Solution

1. Step 1: Write the proportion equation
   139.58 : 192.81 = 111.91 : x
2. Step 2: Convert to fraction form
   139.58/192.81 = 111.91/x
3. Step 3: Cross multiply
   139.58x = 192.81 × 111.91
4. Step 4: Simplify right side
   139.58x = 21,577.37
5. Step 5: Solve for x
   x = 21,577.37/139.58
6. Step 6: Final answer
   x = 154.59