Finding the Fourth Proportional to 12,669.59, 17,390.37 and 12,128.31

Step by Step Solution

1. Step 1: Write the proportion equation
   12,669.59 : 17,390.37 = 12,128.31 : x
2. Step 2: Convert to fraction form
   12,669.59/17,390.37 = 12,128.31/x
3. Step 3: Cross multiply
   12,669.59x = 17,390.37 × 12,128.31
4. Step 4: Simplify right side
   12,669.59x = 210,915,798.37
5. Step 5: Solve for x
   x = 210,915,798.37/12,669.59
6. Step 6: Final answer
   x = 16,647.41