Finding the Fourth Proportional to 139.92, 209.76 and 105.50

Step by Step Solution

1. Step 1: Write the proportion equation
   139.92 : 209.76 = 105.50 : x
2. Step 2: Convert to fraction form
   139.92/209.76 = 105.50/x
3. Step 3: Cross multiply
   139.92x = 209.76 × 105.50
4. Step 4: Simplify right side
   139.92x = 22,128.63
5. Step 5: Solve for x
   x = 22,128.63/139.92
6. Step 6: Final answer
   x = 158.15