Finding the Fourth Proportional to 139,920.61, 209,912.10 and 51,172.15

Step by Step Solution

1. Step 1: Write the proportion equation
   139,920.61 : 209,912.10 = 51,172.15 : x
2. Step 2: Convert to fraction form
   139,920.61/209,912.10 = 51,172.15/x
3. Step 3: Cross multiply
   139,920.61x = 209,912.10 × 51,172.15
4. Step 4: Simplify right side
   139,920.61x = 10,741,653,468.02
5. Step 5: Solve for x
   x = 10,741,653,468.02/139,920.61
6. Step 6: Final answer
   x = 76,769.63