Finding the Fourth Proportional to 9,666.57, 13,340.98 and 5,418.78

Step by Step Solution

1. Step 1: Write the proportion equation
   9,666.57 : 13,340.98 = 5,418.78 : x
2. Step 2: Convert to fraction form
   9,666.57/13,340.98 = 5,418.78/x
3. Step 3: Cross multiply
   9,666.57x = 13,340.98 × 5,418.78
4. Step 4: Simplify right side
   9,666.57x = 72,291,862.18
5. Step 5: Solve for x
   x = 72,291,862.18/9,666.57
6. Step 6: Final answer
   x = 7,478.54