Finding the Fourth Proportional to 12,978.60, 19,439.10 and 10,674.60

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.60 : 19,439.10 = 10,674.60 : x
2. Step 2: Convert to fraction form
   12,978.60/19,439.10 = 10,674.60/x
3. Step 3: Cross multiply
   12,978.60x = 19,439.10 × 10,674.60
4. Step 4: Simplify right side
   12,978.60x = 207,504,616.86
5. Step 5: Solve for x
   x = 207,504,616.86/12,978.60
6. Step 6: Final answer
   x = 15,988.21