Finding the Fourth Proportional to 139.15, 208.71 and 70.72

Step by Step Solution

1. Step 1: Write the proportion equation
   139.15 : 208.71 = 70.72 : x
2. Step 2: Convert to fraction form
   139.15/208.71 = 70.72/x
3. Step 3: Cross multiply
   139.15x = 208.71 × 70.72
4. Step 4: Simplify right side
   139.15x = 14,759.45
5. Step 5: Solve for x
   x = 14,759.45/139.15
6. Step 6: Final answer
   x = 106.07