Finding the Fourth Proportional to 139.72, 192.71 and 90.56

Step by Step Solution

1. Step 1: Write the proportion equation
   139.72 : 192.71 = 90.56 : x
2. Step 2: Convert to fraction form
   139.72/192.71 = 90.56/x
3. Step 3: Cross multiply
   139.72x = 192.71 × 90.56
4. Step 4: Simplify right side
   139.72x = 17,451.82
5. Step 5: Solve for x
   x = 17,451.82/139.72
6. Step 6: Final answer
   x = 124.91