Finding the Fourth Proportional to 139.56, 192.42 and 100.68

Step by Step Solution

1. Step 1: Write the proportion equation
   139.56 : 192.42 = 100.68 : x
2. Step 2: Convert to fraction form
   139.56/192.42 = 100.68/x
3. Step 3: Cross multiply
   139.56x = 192.42 × 100.68
4. Step 4: Simplify right side
   139.56x = 19,372.85
5. Step 5: Solve for x
   x = 19,372.85/139.56
6. Step 6: Final answer
   x = 138.81