Finding the Fourth Proportional to 139.41, 209.25 and 78.63

Step by Step Solution

1. Step 1: Write the proportion equation
   139.41 : 209.25 = 78.63 : x
2. Step 2: Convert to fraction form
   139.41/209.25 = 78.63/x
3. Step 3: Cross multiply
   139.41x = 209.25 × 78.63
4. Step 4: Simplify right side
   139.41x = 16,453.33
5. Step 5: Solve for x
   x = 16,453.33/139.41
6. Step 6: Final answer
   x = 118.02