Finding the Fourth Proportional to 8,128.78, 12,192.90 and 3,445.78

Step by Step Solution

1. Step 1: Write the proportion equation
   8,128.78 : 12,192.90 = 3,445.78 : x
2. Step 2: Convert to fraction form
   8,128.78/12,192.90 = 3,445.78/x
3. Step 3: Cross multiply
   8,128.78x = 12,192.90 × 3,445.78
4. Step 4: Simplify right side
   8,128.78x = 42,014,036.88
5. Step 5: Solve for x
   x = 42,014,036.88/8,128.78
6. Step 6: Final answer
   x = 5,168.55