Finding the Fourth Proportional to 139.24, 208.69 and 78.29

Step by Step Solution

1. Step 1: Write the proportion equation
   139.24 : 208.69 = 78.29 : x
2. Step 2: Convert to fraction form
   139.24/208.69 = 78.29/x
3. Step 3: Cross multiply
   139.24x = 208.69 × 78.29
4. Step 4: Simplify right side
   139.24x = 16,338.34
5. Step 5: Solve for x
   x = 16,338.34/139.24
6. Step 6: Final answer
   x = 117.34