Finding the Fourth Proportional to 8,106.40, 10,978.20 and 8,106.40

Step by Step Solution

1. Step 1: Write the proportion equation
   8,106.40 : 10,978.20 = 8,106.40 : x
2. Step 2: Convert to fraction form
   8,106.40/10,978.20 = 8,106.40/x
3. Step 3: Cross multiply
   8,106.40x = 10,978.20 × 8,106.40
4. Step 4: Simplify right side
   8,106.40x = 88,993,680.48
5. Step 5: Solve for x
   x = 88,993,680.48/8,106.40
6. Step 6: Final answer
   x = 10,978.20