Finding the Fourth Proportional to 9,315.78, 12,857.60 and 5,339.55

Step by Step Solution

1. Step 1: Write the proportion equation
   9,315.78 : 12,857.60 = 5,339.55 : x
2. Step 2: Convert to fraction form
   9,315.78/12,857.60 = 5,339.55/x
3. Step 3: Cross multiply
   9,315.78x = 12,857.60 × 5,339.55
4. Step 4: Simplify right side
   9,315.78x = 68,653,771.38
5. Step 5: Solve for x
   x = 68,653,771.38/9,315.78
6. Step 6: Final answer
   x = 7,369.63