Finding the Fourth Proportional to 12,978.57, 17,911.76 and 7,946.12

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.57 : 17,911.76 = 7,946.12 : x
2. Step 2: Convert to fraction form
   12,978.57/17,911.76 = 7,946.12/x
3. Step 3: Cross multiply
   12,978.57x = 17,911.76 × 7,946.12
4. Step 4: Simplify right side
   12,978.57x = 142,328,865.08
5. Step 5: Solve for x
   x = 142,328,865.08/12,978.57
6. Step 6: Final answer
   x = 10,966.45