Finding the Fourth Proportional to 139.23, 192.15 and 90.12

Step by Step Solution

1. Step 1: Write the proportion equation
   139.23 : 192.15 = 90.12 : x
2. Step 2: Convert to fraction form
   139.23/192.15 = 90.12/x
3. Step 3: Cross multiply
   139.23x = 192.15 × 90.12
4. Step 4: Simplify right side
   139.23x = 17,316.56
5. Step 5: Solve for x
   x = 17,316.56/139.23
6. Step 6: Final answer
   x = 124.37