Finding the Fourth Proportional to 15,128.91, 20,879.73 and 9,160.43

Step by Step Solution

1. Step 1: Write the proportion equation
   15,128.91 : 20,879.73 = 9,160.43 : x
2. Step 2: Convert to fraction form
   15,128.91/20,879.73 = 9,160.43/x
3. Step 3: Cross multiply
   15,128.91x = 20,879.73 × 9,160.43
4. Step 4: Simplify right side
   15,128.91x = 191,267,200.69
5. Step 5: Solve for x
   x = 191,267,200.69/15,128.91
6. Step 6: Final answer
   x = 12,642.50