Finding the Fourth Proportional to 12,615.34, 17,405.67 and 8,139.28

Step by Step Solution

1. Step 1: Write the proportion equation
   12,615.34 : 17,405.67 = 8,139.28 : x
2. Step 2: Convert to fraction form
   12,615.34/17,405.67 = 8,139.28/x
3. Step 3: Cross multiply
   12,615.34x = 17,405.67 × 8,139.28
4. Step 4: Simplify right side
   12,615.34x = 141,669,621.72
5. Step 5: Solve for x
   x = 141,669,621.72/12,615.34
6. Step 6: Final answer
   x = 11,229.95