Finding the Fourth Proportional to 31,843.36, 47,756.85 and 13,128.72

Step by Step Solution

1. Step 1: Write the proportion equation
   31,843.36 : 47,756.85 = 13,128.72 : x
2. Step 2: Convert to fraction form
   31,843.36/47,756.85 = 13,128.72/x
3. Step 3: Cross multiply
   31,843.36x = 47,756.85 × 13,128.72
4. Step 4: Simplify right side
   31,843.36x = 626,986,311.73
5. Step 5: Solve for x
   x = 626,986,311.73/31,843.36
6. Step 6: Final answer
   x = 19,689.70