Finding the Fourth Proportional to 13,128.86, 18,112.47 and 8,021.72

Step by Step Solution

1. Step 1: Write the proportion equation
   13,128.86 : 18,112.47 = 8,021.72 : x
2. Step 2: Convert to fraction form
   13,128.86/18,112.47 = 8,021.72/x
3. Step 3: Cross multiply
   13,128.86x = 18,112.47 × 8,021.72
4. Step 4: Simplify right side
   13,128.86x = 145,293,162.85
5. Step 5: Solve for x
   x = 145,293,162.85/13,128.86
6. Step 6: Final answer
   x = 11,066.70