Finding the Fourth Proportional to 5,172.75, 7,139.61 and 3,078.09

Step by Step Solution

1. Step 1: Write the proportion equation
   5,172.75 : 7,139.61 = 3,078.09 : x
2. Step 2: Convert to fraction form
   5,172.75/7,139.61 = 3,078.09/x
3. Step 3: Cross multiply
   5,172.75x = 7,139.61 × 3,078.09
4. Step 4: Simplify right side
   5,172.75x = 21,976,362.14
5. Step 5: Solve for x
   x = 21,976,362.14/5,172.75
6. Step 6: Final answer
   x = 4,248.49