Finding the Fourth Proportional to 139.30, 192.24 and 90.30

Step by Step Solution

1. Step 1: Write the proportion equation
   139.30 : 192.24 = 90.30 : x
2. Step 2: Convert to fraction form
   139.30/192.24 = 90.30/x
3. Step 3: Cross multiply
   139.30x = 192.24 × 90.30
4. Step 4: Simplify right side
   139.30x = 17,359.27
5. Step 5: Solve for x
   x = 17,359.27/139.30
6. Step 6: Final answer
   x = 124.62