Finding the Fourth Proportional to 18,938.72, 28,414.38 and 8,407.28

Step by Step Solution

1. Step 1: Write the proportion equation
   18,938.72 : 28,414.38 = 8,407.28 : x
2. Step 2: Convert to fraction form
   18,938.72/28,414.38 = 8,407.28/x
3. Step 3: Cross multiply
   18,938.72x = 28,414.38 × 8,407.28
4. Step 4: Simplify right side
   18,938.72x = 238,887,648.69
5. Step 5: Solve for x
   x = 238,887,648.69/18,938.72
6. Step 6: Final answer
   x = 12,613.72