Finding the Fourth Proportional to 139.72, 192.83 and 80.72

Step by Step Solution

1. Step 1: Write the proportion equation
   139.72 : 192.83 = 80.72 : x
2. Step 2: Convert to fraction form
   139.72/192.83 = 80.72/x
3. Step 3: Cross multiply
   139.72x = 192.83 × 80.72
4. Step 4: Simplify right side
   139.72x = 15,565.14
5. Step 5: Solve for x
   x = 15,565.14/139.72
6. Step 6: Final answer
   x = 111.40