Finding the Fourth Proportional to 9,920.28, 13,689.96 and 5,728.56

Step by Step Solution

1. Step 1: Write the proportion equation
   9,920.28 : 13,689.96 = 5,728.56 : x
2. Step 2: Convert to fraction form
   9,920.28/13,689.96 = 5,728.56/x
3. Step 3: Cross multiply
   9,920.28x = 13,689.96 × 5,728.56
4. Step 4: Simplify right side
   9,920.28x = 78,423,757.26
5. Step 5: Solve for x
   x = 78,423,757.26/9,920.28
6. Step 6: Final answer
   x = 7,905.40