Finding the Fourth Proportional to 8,778.11, 12,113.82 and 5,420.15

Step by Step Solution

1. Step 1: Write the proportion equation
   8,778.11 : 12,113.82 = 5,420.15 : x
2. Step 2: Convert to fraction form
   8,778.11/12,113.82 = 5,420.15/x
3. Step 3: Cross multiply
   8,778.11x = 12,113.82 × 5,420.15
4. Step 4: Simplify right side
   8,778.11x = 65,658,706.33
5. Step 5: Solve for x
   x = 65,658,706.33/8,778.11
6. Step 6: Final answer
   x = 7,479.83