Finding the Fourth Proportional to 12,945.63, 17,866.89 and 7,912.80

Step by Step Solution

1. Step 1: Write the proportion equation
   12,945.63 : 17,866.89 = 7,912.80 : x
2. Step 2: Convert to fraction form
   12,945.63/17,866.89 = 7,912.80/x
3. Step 3: Cross multiply
   12,945.63x = 17,866.89 × 7,912.80
4. Step 4: Simplify right side
   12,945.63x = 141,377,127.19
5. Step 5: Solve for x
   x = 141,377,127.19/12,945.63
6. Step 6: Final answer
   x = 10,920.84