Finding the Fourth Proportional to 15,781.72, 21,759.42 and 12,786.52

Step by Step Solution

1. Step 1: Write the proportion equation
   15,781.72 : 21,759.42 = 12,786.52 : x
2. Step 2: Convert to fraction form
   15,781.72/21,759.42 = 12,786.52/x
3. Step 3: Cross multiply
   15,781.72x = 21,759.42 × 12,786.52
4. Step 4: Simplify right side
   15,781.72x = 278,227,259.02
5. Step 5: Solve for x
   x = 278,227,259.02/15,781.72
6. Step 6: Final answer
   x = 17,629.72