Finding the Fourth Proportional to 139,396.85, 192,368.12 and 78,978.68

Step by Step Solution

1. Step 1: Write the proportion equation
   139,396.85 : 192,368.12 = 78,978.68 : x
2. Step 2: Convert to fraction form
   139,396.85/192,368.12 = 78,978.68/x
3. Step 3: Cross multiply
   139,396.85x = 192,368.12 × 78,978.68
4. Step 4: Simplify right side
   139,396.85x = 15,192,978,834.95
5. Step 5: Solve for x
   x = 15,192,978,834.95/139,396.85
6. Step 6: Final answer
   x = 108,990.84