Finding the Fourth Proportional to 12,907.89, 17,820.65 and 8,439.12

Step by Step Solution

1. Step 1: Write the proportion equation
   12,907.89 : 17,820.65 = 8,439.12 : x
2. Step 2: Convert to fraction form
   12,907.89/17,820.65 = 8,439.12/x
3. Step 3: Cross multiply
   12,907.89x = 17,820.65 × 8,439.12
4. Step 4: Simplify right side
   12,907.89x = 150,390,603.83
5. Step 5: Solve for x
   x = 150,390,603.83/12,907.89
6. Step 6: Final answer
   x = 11,651.06