Finding the Fourth Proportional to 15,788.89, 21,788.68 and 8,715.31

Step by Step Solution

1. Step 1: Write the proportion equation
   15,788.89 : 21,788.68 = 8,715.31 : x
2. Step 2: Convert to fraction form
   15,788.89/21,788.68 = 8,715.31/x
3. Step 3: Cross multiply
   15,788.89x = 21,788.68 × 8,715.31
4. Step 4: Simplify right side
   15,788.89x = 189,895,100.69
5. Step 5: Solve for x
   x = 189,895,100.69/15,788.89
6. Step 6: Final answer
   x = 12,027.13