Finding the Fourth Proportional to 139.51, 192.59 and 90.43

Step by Step Solution

1. Step 1: Write the proportion equation
   139.51 : 192.59 = 90.43 : x
2. Step 2: Convert to fraction form
   139.51/192.59 = 90.43/x
3. Step 3: Cross multiply
   139.51x = 192.59 × 90.43
4. Step 4: Simplify right side
   139.51x = 17,414.95
5. Step 5: Solve for x
   x = 17,414.95/139.51
6. Step 6: Final answer
   x = 124.83