Finding the Fourth Proportional to 9,355.15, 12,911.78 and 5,578.54

Step by Step Solution

1. Step 1: Write the proportion equation
   9,355.15 : 12,911.78 = 5,578.54 : x
2. Step 2: Convert to fraction form
   9,355.15/12,911.78 = 5,578.54/x
3. Step 3: Cross multiply
   9,355.15x = 12,911.78 × 5,578.54
4. Step 4: Simplify right side
   9,355.15x = 72,028,881.20
5. Step 5: Solve for x
   x = 72,028,881.20/9,355.15
6. Step 6: Final answer
   x = 7,699.38