Finding the Fourth Proportional to 139.72, 192.52 and 121.20

Step by Step Solution

1. Step 1: Write the proportion equation
   139.72 : 192.52 = 121.20 : x
2. Step 2: Convert to fraction form
   139.72/192.52 = 121.20/x
3. Step 3: Cross multiply
   139.72x = 192.52 × 121.20
4. Step 4: Simplify right side
   139.72x = 23,333.42
5. Step 5: Solve for x
   x = 23,333.42/139.72
6. Step 6: Final answer
   x = 167.00