Finding the Fourth Proportional to 139.88, 209.89 and 105.63

Step by Step Solution

1. Step 1: Write the proportion equation
   139.88 : 209.89 = 105.63 : x
2. Step 2: Convert to fraction form
   139.88/209.89 = 105.63/x
3. Step 3: Cross multiply
   139.88x = 209.89 × 105.63
4. Step 4: Simplify right side
   139.88x = 22,170.62
5. Step 5: Solve for x
   x = 22,170.62/139.88
6. Step 6: Final answer
   x = 158.50