Finding the Fourth Proportional to 9,816.80, 14,715.60 and 5,139.20

Step by Step Solution

1. Step 1: Write the proportion equation
   9,816.80 : 14,715.60 = 5,139.20 : x
2. Step 2: Convert to fraction form
   9,816.80/14,715.60 = 5,139.20/x
3. Step 3: Cross multiply
   9,816.80x = 14,715.60 × 5,139.20
4. Step 4: Simplify right side
   9,816.80x = 75,626,411.52
5. Step 5: Solve for x
   x = 75,626,411.52/9,816.80
6. Step 6: Final answer
   x = 7,703.77