Finding the Fourth Proportional to 139.98, 209.88 and 103.86

Step by Step Solution

1. Step 1: Write the proportion equation
   139.98 : 209.88 = 103.86 : x
2. Step 2: Convert to fraction form
   139.98/209.88 = 103.86/x
3. Step 3: Cross multiply
   139.98x = 209.88 × 103.86
4. Step 4: Simplify right side
   139.98x = 21,798.14
5. Step 5: Solve for x
   x = 21,798.14/139.98
6. Step 6: Final answer
   x = 155.72