Finding the Fourth Proportional to 9,920.82, 14,877.72 and 7,139.20

Step by Step Solution

1. Step 1: Write the proportion equation
   9,920.82 : 14,877.72 = 7,139.20 : x
2. Step 2: Convert to fraction form
   9,920.82/14,877.72 = 7,139.20/x
3. Step 3: Cross multiply
   9,920.82x = 14,877.72 × 7,139.20
4. Step 4: Simplify right side
   9,920.82x = 106,215,018.62
5. Step 5: Solve for x
   x = 106,215,018.62/9,920.82
6. Step 6: Final answer
   x = 10,706.27