Finding the Fourth Proportional to 12,128.82, 18,164.06 and 8,221.38

Step by Step Solution

1. Step 1: Write the proportion equation
   12,128.82 : 18,164.06 = 8,221.38 : x
2. Step 2: Convert to fraction form
   12,128.82/18,164.06 = 8,221.38/x
3. Step 3: Cross multiply
   12,128.82x = 18,164.06 × 8,221.38
4. Step 4: Simplify right side
   12,128.82x = 149,333,639.60
5. Step 5: Solve for x
   x = 149,333,639.60/12,128.82
6. Step 6: Final answer
   x = 12,312.30