Finding the Fourth Proportional to 23,139.12, 31,931.94 and 12,528.72

Step by Step Solution

1. Step 1: Write the proportion equation
   23,139.12 : 31,931.94 = 12,528.72 : x
2. Step 2: Convert to fraction form
   23,139.12/31,931.94 = 12,528.72/x
3. Step 3: Cross multiply
   23,139.12x = 31,931.94 × 12,528.72
4. Step 4: Simplify right side
   23,139.12x = 400,066,335.32
5. Step 5: Solve for x
   x = 400,066,335.32/23,139.12
6. Step 6: Final answer
   x = 17,289.61