Finding the Fourth Proportional to 12,978.88, 17,916.64 and 9,993.60

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.88 : 17,916.64 = 9,993.60 : x
2. Step 2: Convert to fraction form
   12,978.88/17,916.64 = 9,993.60/x
3. Step 3: Cross multiply
   12,978.88x = 17,916.64 × 9,993.60
4. Step 4: Simplify right side
   12,978.88x = 179,051,733.50
5. Step 5: Solve for x
   x = 179,051,733.50/12,978.88
6. Step 6: Final answer
   x = 13,795.62