Finding the Fourth Proportional to 139.37, 192.20 and 90.19

Step by Step Solution

1. Step 1: Write the proportion equation
   139.37 : 192.20 = 90.19 : x
2. Step 2: Convert to fraction form
   139.37/192.20 = 90.19/x
3. Step 3: Cross multiply
   139.37x = 192.20 × 90.19
4. Step 4: Simplify right side
   139.37x = 17,333.59
5. Step 5: Solve for x
   x = 17,333.59/139.37
6. Step 6: Final answer
   x = 124.38