Finding the Fourth Proportional to 139.31, 192.27 and 90.20

Step by Step Solution

1. Step 1: Write the proportion equation
   139.31 : 192.27 = 90.20 : x
2. Step 2: Convert to fraction form
   139.31/192.27 = 90.20/x
3. Step 3: Cross multiply
   139.31x = 192.27 × 90.20
4. Step 4: Simplify right side
   139.31x = 17,342.75
5. Step 5: Solve for x
   x = 17,342.75/139.31
6. Step 6: Final answer
   x = 124.49