Finding the Fourth Proportional to 139,990.80, 209,931.60 and 61,051.20

Step by Step Solution

1. Step 1: Write the proportion equation
   139,990.80 : 209,931.60 = 61,051.20 : x
2. Step 2: Convert to fraction form
   139,990.80/209,931.60 = 61,051.20/x
3. Step 3: Cross multiply
   139,990.80x = 209,931.60 × 61,051.20
4. Step 4: Simplify right side
   139,990.80x = 12,816,576,097.92
5. Step 5: Solve for x
   x = 12,816,576,097.92/139,990.80
6. Step 6: Final answer
   x = 91,552.99