Finding the Fourth Proportional to 12,857.32, 17,744.42 and 7,821.90

Step by Step Solution

1. Step 1: Write the proportion equation
   12,857.32 : 17,744.42 = 7,821.90 : x
2. Step 2: Convert to fraction form
   12,857.32/17,744.42 = 7,821.90/x
3. Step 3: Cross multiply
   12,857.32x = 17,744.42 × 7,821.90
4. Step 4: Simplify right side
   12,857.32x = 138,795,078.80
5. Step 5: Solve for x
   x = 138,795,078.80/12,857.32
6. Step 6: Final answer
   x = 10,795.02