Finding the Fourth Proportional to 8,305.82, 12,478.18 and 7,139.42

Step by Step Solution

1. Step 1: Write the proportion equation
   8,305.82 : 12,478.18 = 7,139.42 : x
2. Step 2: Convert to fraction form
   8,305.82/12,478.18 = 7,139.42/x
3. Step 3: Cross multiply
   8,305.82x = 12,478.18 × 7,139.42
4. Step 4: Simplify right side
   8,305.82x = 89,086,967.86
5. Step 5: Solve for x
   x = 89,086,967.86/8,305.82
6. Step 6: Final answer
   x = 10,725.85