Finding the Fourth Proportional to 12,138.72, 18,200.40 and 5,116.80

Step by Step Solution

1. Step 1: Write the proportion equation
   12,138.72 : 18,200.40 = 5,116.80 : x
2. Step 2: Convert to fraction form
   12,138.72/18,200.40 = 5,116.80/x
3. Step 3: Cross multiply
   12,138.72x = 18,200.40 × 5,116.80
4. Step 4: Simplify right side
   12,138.72x = 93,127,806.72
5. Step 5: Solve for x
   x = 93,127,806.72/12,138.72
6. Step 6: Final answer
   x = 7,671.96