Finding the Fourth Proportional to 12,978.78, 17,912.12 and 7,946.39

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.78 : 17,912.12 = 7,946.39 : x
2. Step 2: Convert to fraction form
   12,978.78/17,912.12 = 7,946.39/x
3. Step 3: Cross multiply
   12,978.78x = 17,912.12 × 7,946.39
4. Step 4: Simplify right side
   12,978.78x = 142,336,691.25
5. Step 5: Solve for x
   x = 142,336,691.25/12,978.78
6. Step 6: Final answer
   x = 10,966.88