Finding the Fourth Proportional to 139.65, 192.68 and 89.86

Step by Step Solution

1. Step 1: Write the proportion equation
   139.65 : 192.68 = 89.86 : x
2. Step 2: Convert to fraction form
   139.65/192.68 = 89.86/x
3. Step 3: Cross multiply
   139.65x = 192.68 × 89.86
4. Step 4: Simplify right side
   139.65x = 17,314.81
5. Step 5: Solve for x
   x = 17,314.81/139.65
6. Step 6: Final answer
   x = 123.99