Finding the Fourth Proportional to 8,613.12, 12,900.16 and 8,418.72

Step by Step Solution

1. Step 1: Write the proportion equation
   8,613.12 : 12,900.16 = 8,418.72 : x
2. Step 2: Convert to fraction form
   8,613.12/12,900.16 = 8,418.72/x
3. Step 3: Cross multiply
   8,613.12x = 12,900.16 × 8,418.72
4. Step 4: Simplify right side
   8,613.12x = 108,602,835.00
5. Step 5: Solve for x
   x = 108,602,835.00/8,613.12
6. Step 6: Final answer
   x = 12,609.00