Finding the Fourth Proportional to 139.55, 192.38 and 121.86

Step by Step Solution

1. Step 1: Write the proportion equation
   139.55 : 192.38 = 121.86 : x
2. Step 2: Convert to fraction form
   139.55/192.38 = 121.86/x
3. Step 3: Cross multiply
   139.55x = 192.38 × 121.86
4. Step 4: Simplify right side
   139.55x = 23,442.82
5. Step 5: Solve for x
   x = 23,442.82/139.55
6. Step 6: Final answer
   x = 167.99