Finding the Fourth Proportional to 12,786.89, 17,645.91 and 7,122.72

Step by Step Solution

1. Step 1: Write the proportion equation
   12,786.89 : 17,645.91 = 7,122.72 : x
2. Step 2: Convert to fraction form
   12,786.89/17,645.91 = 7,122.72/x
3. Step 3: Cross multiply
   12,786.89x = 17,645.91 × 7,122.72
4. Step 4: Simplify right side
   12,786.89x = 125,686,915.54
5. Step 5: Solve for x
   x = 125,686,915.54/12,786.89
6. Step 6: Final answer
   x = 9,829.36