Finding the Fourth Proportional to 139.89, 209.69 and 71.35

Step by Step Solution

1. Step 1: Write the proportion equation
   139.89 : 209.69 = 71.35 : x
2. Step 2: Convert to fraction form
   139.89/209.69 = 71.35/x
3. Step 3: Cross multiply
   139.89x = 209.69 × 71.35
4. Step 4: Simplify right side
   139.89x = 14,960.77
5. Step 5: Solve for x
   x = 14,960.77/139.89
6. Step 6: Final answer
   x = 106.94