Finding the Fourth Proportional to 12,139.20, 16,956 and 12,139.20

Step by Step Solution

1. Step 1: Write the proportion equation
   12,139.20 : 16,956 = 12,139.20 : x
2. Step 2: Convert to fraction form
   12,139.20/16,956 = 12,139.20/x
3. Step 3: Cross multiply
   12,139.20x = 16,956 × 12,139.20
4. Step 4: Simplify right side
   12,139.20x = 205,832,275.20
5. Step 5: Solve for x
   x = 205,832,275.20/12,139.20
6. Step 6: Final answer
   x = 16,956