Finding the Fourth Proportional to 139.02, 191.79 and 89.86

Step by Step Solution

1. Step 1: Write the proportion equation
   139.02 : 191.79 = 89.86 : x
2. Step 2: Convert to fraction form
   139.02/191.79 = 89.86/x
3. Step 3: Cross multiply
   139.02x = 191.79 × 89.86
4. Step 4: Simplify right side
   139.02x = 17,234.25
5. Step 5: Solve for x
   x = 17,234.25/139.02
6. Step 6: Final answer
   x = 123.97