Finding the Fourth Proportional to 15,789.39, 21,789.38 and 8,715.81

Step by Step Solution

1. Step 1: Write the proportion equation
   15,789.39 : 21,789.38 = 8,715.81 : x
2. Step 2: Convert to fraction form
   15,789.39/21,789.38 = 8,715.81/x
3. Step 3: Cross multiply
   15,789.39x = 21,789.38 × 8,715.81
4. Step 4: Simplify right side
   15,789.39x = 189,912,052.52
5. Step 5: Solve for x
   x = 189,912,052.52/15,789.39
6. Step 6: Final answer
   x = 12,027.83