Finding the Fourth Proportional to 13,435.72, 18,536.38 and 8,128.60

Step by Step Solution

1. Step 1: Write the proportion equation
   13,435.72 : 18,536.38 = 8,128.60 : x
2. Step 2: Convert to fraction form
   13,435.72/18,536.38 = 8,128.60/x
3. Step 3: Cross multiply
   13,435.72x = 18,536.38 × 8,128.60
4. Step 4: Simplify right side
   13,435.72x = 150,674,751.81
5. Step 5: Solve for x
   x = 150,674,751.81/13,435.72
6. Step 6: Final answer
   x = 11,214.49