Finding the Fourth Proportional to 31,391.44, 47,091 and 12,928.72

Step by Step Solution

1. Step 1: Write the proportion equation
   31,391.44 : 47,091 = 12,928.72 : x
2. Step 2: Convert to fraction form
   31,391.44/47,091 = 12,928.72/x
3. Step 3: Cross multiply
   31,391.44x = 47,091 × 12,928.72
4. Step 4: Simplify right side
   31,391.44x = 608,826,353.52
5. Step 5: Solve for x
   x = 608,826,353.52/31,391.44
6. Step 6: Final answer
   x = 19,394.66