Finding the Fourth Proportional to 12,128.76, 18,200.16 and 5,108.28

Step by Step Solution

1. Step 1: Write the proportion equation
   12,128.76 : 18,200.16 = 5,108.28 : x
2. Step 2: Convert to fraction form
   12,128.76/18,200.16 = 5,108.28/x
3. Step 3: Cross multiply
   12,128.76x = 18,200.16 × 5,108.28
4. Step 4: Simplify right side
   12,128.76x = 92,971,513.32
5. Step 5: Solve for x
   x = 92,971,513.32/12,128.76
6. Step 6: Final answer
   x = 7,665.38