Finding the Fourth Proportional to 8,871.28, 13,258.79 and 8,170.72

Step by Step Solution

1. Step 1: Write the proportion equation
   8,871.28 : 13,258.79 = 8,170.72 : x
2. Step 2: Convert to fraction form
   8,871.28/13,258.79 = 8,170.72/x
3. Step 3: Cross multiply
   8,871.28x = 13,258.79 × 8,170.72
4. Step 4: Simplify right side
   8,871.28x = 108,333,860.63
5. Step 5: Solve for x
   x = 108,333,860.63/8,871.28
6. Step 6: Final answer
   x = 12,211.75