Finding the Fourth Proportional to 12,821.76, 17,687.52 and 7,784.64

Step by Step Solution

1. Step 1: Write the proportion equation
   12,821.76 : 17,687.52 = 7,784.64 : x
2. Step 2: Convert to fraction form
   12,821.76/17,687.52 = 7,784.64/x
3. Step 3: Cross multiply
   12,821.76x = 17,687.52 × 7,784.64
4. Step 4: Simplify right side
   12,821.76x = 137,690,975.69
5. Step 5: Solve for x
   x = 137,690,975.69/12,821.76
6. Step 6: Final answer
   x = 10,738.85