Finding the Fourth Proportional to 139.65, 192.72 and 89.85

Step by Step Solution

1. Step 1: Write the proportion equation
   139.65 : 192.72 = 89.85 : x
2. Step 2: Convert to fraction form
   139.65/192.72 = 89.85/x
3. Step 3: Cross multiply
   139.65x = 192.72 × 89.85
4. Step 4: Simplify right side
   139.65x = 17,315.89
5. Step 5: Solve for x
   x = 17,315.89/139.65
6. Step 6: Final answer
   x = 123.99