Finding the Fourth Proportional to 12,908.81, 17,809.89 and 7,871.19

Step by Step Solution

1. Step 1: Write the proportion equation
   12,908.81 : 17,809.89 = 7,871.19 : x
2. Step 2: Convert to fraction form
   12,908.81/17,809.89 = 7,871.19/x
3. Step 3: Cross multiply
   12,908.81x = 17,809.89 × 7,871.19
4. Step 4: Simplify right side
   12,908.81x = 140,185,028.07
5. Step 5: Solve for x
   x = 140,185,028.07/12,908.81
6. Step 6: Final answer
   x = 10,859.64