Finding the Fourth Proportional to 9,290.80, 12,787.92 and 8,404.72

Step by Step Solution

1. Step 1: Write the proportion equation
   9,290.80 : 12,787.92 = 8,404.72 : x
2. Step 2: Convert to fraction form
   9,290.80/12,787.92 = 8,404.72/x
3. Step 3: Cross multiply
   9,290.80x = 12,787.92 × 8,404.72
4. Step 4: Simplify right side
   9,290.80x = 107,478,886.98
5. Step 5: Solve for x
   x = 107,478,886.98/9,290.80
6. Step 6: Final answer
   x = 11,568.31