Finding the Fourth Proportional to 139.77, 209.43 and 105.50

Step by Step Solution

1. Step 1: Write the proportion equation
   139.77 : 209.43 = 105.50 : x
2. Step 2: Convert to fraction form
   139.77/209.43 = 105.50/x
3. Step 3: Cross multiply
   139.77x = 209.43 × 105.50
4. Step 4: Simplify right side
   139.77x = 22,095.39
5. Step 5: Solve for x
   x = 22,095.39/139.77
6. Step 6: Final answer
   x = 158.08