Finding the Fourth Proportional to 13,112.91, 18,090.63 and 8,638.83

Step by Step Solution

1. Step 1: Write the proportion equation
   13,112.91 : 18,090.63 = 8,638.83 : x
2. Step 2: Convert to fraction form
   13,112.91/18,090.63 = 8,638.83/x
3. Step 3: Cross multiply
   13,112.91x = 18,090.63 × 8,638.83
4. Step 4: Simplify right side
   13,112.91x = 156,281,877.16
5. Step 5: Solve for x
   x = 156,281,877.16/13,112.91
6. Step 6: Final answer
   x = 11,918.17