Finding the Fourth Proportional to 21,788.80, 32,687.52 and 8,638.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,788.80 : 32,687.52 = 8,638.72 : x
2. Step 2: Convert to fraction form
   21,788.80/32,687.52 = 8,638.72/x
3. Step 3: Cross multiply
   21,788.80x = 32,687.52 × 8,638.72
4. Step 4: Simplify right side
   21,788.80x = 282,378,332.77
5. Step 5: Solve for x
   x = 282,378,332.77/21,788.80
6. Step 6: Final answer
   x = 12,959.79