Finding the Fourth Proportional to 9,115.72, 12,579.78 and 5,389

Step by Step Solution

1. Step 1: Write the proportion equation
   9,115.72 : 12,579.78 = 5,389 : x
2. Step 2: Convert to fraction form
   9,115.72/12,579.78 = 5,389/x
3. Step 3: Cross multiply
   9,115.72x = 12,579.78 × 5,389
4. Step 4: Simplify right side
   9,115.72x = 67,792,434.42
5. Step 5: Solve for x
   x = 67,792,434.42/9,115.72
6. Step 6: Final answer
   x = 7,436.87