Finding the Fourth Proportional to 139.77, 192.83 and 90.69

Step by Step Solution

1. Step 1: Write the proportion equation
   139.77 : 192.83 = 90.69 : x
2. Step 2: Convert to fraction form
   139.77/192.83 = 90.69/x
3. Step 3: Cross multiply
   139.77x = 192.83 × 90.69
4. Step 4: Simplify right side
   139.77x = 17,487.75
5. Step 5: Solve for x
   x = 17,487.75/139.77
6. Step 6: Final answer
   x = 125.12