Finding the Fourth Proportional to 139.68, 192.69 and 89.91

Step by Step Solution

1. Step 1: Write the proportion equation
   139.68 : 192.69 = 89.91 : x
2. Step 2: Convert to fraction form
   139.68/192.69 = 89.91/x
3. Step 3: Cross multiply
   139.68x = 192.69 × 89.91
4. Step 4: Simplify right side
   139.68x = 17,324.76
5. Step 5: Solve for x
   x = 17,324.76/139.68
6. Step 6: Final answer
   x = 124.03