Finding the Fourth Proportional to 12,928.72, 17,836.32 and 8,211.28

Step by Step Solution

1. Step 1: Write the proportion equation
   12,928.72 : 17,836.32 = 8,211.28 : x
2. Step 2: Convert to fraction form
   12,928.72/17,836.32 = 8,211.28/x
3. Step 3: Cross multiply
   12,928.72x = 17,836.32 × 8,211.28
4. Step 4: Simplify right side
   12,928.72x = 146,459,017.69
5. Step 5: Solve for x
   x = 146,459,017.69/12,928.72
6. Step 6: Final answer
   x = 11,328.19