Finding the Fourth Proportional to 13,320.78, 19,981.16 and 3,960.76

Step by Step Solution

1. Step 1: Write the proportion equation
   13,320.78 : 19,981.16 = 3,960.76 : x
2. Step 2: Convert to fraction form
   13,320.78/19,981.16 = 3,960.76/x
3. Step 3: Cross multiply
   13,320.78x = 19,981.16 × 3,960.76
4. Step 4: Simplify right side
   13,320.78x = 79,140,509.52
5. Step 5: Solve for x
   x = 79,140,509.52/13,320.78
6. Step 6: Final answer
   x = 5,941.13