Finding the Fourth Proportional to 9,108.10, 12,780.50 and 9,108.10

Step by Step Solution

1. Step 1: Write the proportion equation
   9,108.10 : 12,780.50 = 9,108.10 : x
2. Step 2: Convert to fraction form
   9,108.10/12,780.50 = 9,108.10/x
3. Step 3: Cross multiply
   9,108.10x = 12,780.50 × 9,108.10
4. Step 4: Simplify right side
   9,108.10x = 116,406,072.05
5. Step 5: Solve for x
   x = 116,406,072.05/9,108.10
6. Step 6: Final answer
   x = 12,780.50