Finding the Fourth Proportional to 8,919.72, 12,315.78 and 8,256.28

Step by Step Solution

1. Step 1: Write the proportion equation
   8,919.72 : 12,315.78 = 8,256.28 : x
2. Step 2: Convert to fraction form
   8,919.72/12,315.78 = 8,256.28/x
3. Step 3: Cross multiply
   8,919.72x = 12,315.78 × 8,256.28
4. Step 4: Simplify right side
   8,919.72x = 101,682,528.10
5. Step 5: Solve for x
   x = 101,682,528.10/8,919.72
6. Step 6: Final answer
   x = 11,399.74