Finding the Fourth Proportional to 8,890.82, 13,316.78 and 5,420.78

Step by Step Solution

1. Step 1: Write the proportion equation
   8,890.82 : 13,316.78 = 5,420.78 : x
2. Step 2: Convert to fraction form
   8,890.82/13,316.78 = 5,420.78/x
3. Step 3: Cross multiply
   8,890.82x = 13,316.78 × 5,420.78
4. Step 4: Simplify right side
   8,890.82x = 72,187,334.69
5. Step 5: Solve for x
   x = 72,187,334.69/8,890.82
6. Step 6: Final answer
   x = 8,119.31