Finding the Fourth Proportional to 9,128.70, 12,806.10 and 9,128.70

Step by Step Solution

1. Step 1: Write the proportion equation
   9,128.70 : 12,806.10 = 9,128.70 : x
2. Step 2: Convert to fraction form
   9,128.70/12,806.10 = 9,128.70/x
3. Step 3: Cross multiply
   9,128.70x = 12,806.10 × 9,128.70
4. Step 4: Simplify right side
   9,128.70x = 116,903,045.07
5. Step 5: Solve for x
   x = 116,903,045.07/9,128.70
6. Step 6: Final answer
   x = 12,806.10