Finding the Fourth Proportional to 9,120.81, 13,685.31 and 5,616.15

Step by Step Solution

1. Step 1: Write the proportion equation
   9,120.81 : 13,685.31 = 5,616.15 : x
2. Step 2: Convert to fraction form
   9,120.81/13,685.31 = 5,616.15/x
3. Step 3: Cross multiply
   9,120.81x = 13,685.31 × 5,616.15
4. Step 4: Simplify right side
   9,120.81x = 76,858,753.76
5. Step 5: Solve for x
   x = 76,858,753.76/9,120.81
6. Step 6: Final answer
   x = 8,426.75