Finding the Fourth Proportional to 12,978.18, 17,884.90 and 9,435.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.18 : 17,884.90 = 9,435.78 : x
2. Step 2: Convert to fraction form
   12,978.18/17,884.90 = 9,435.78/x
3. Step 3: Cross multiply
   12,978.18x = 17,884.90 × 9,435.78
4. Step 4: Simplify right side
   12,978.18x = 168,757,981.72
5. Step 5: Solve for x
   x = 168,757,981.72/12,978.18
6. Step 6: Final answer
   x = 13,003.21