Finding the Fourth Proportional to 9,404.56, 12,978.02 and 5,155.40

Step by Step Solution

1. Step 1: Write the proportion equation
   9,404.56 : 12,978.02 = 5,155.40 : x
2. Step 2: Convert to fraction form
   9,404.56/12,978.02 = 5,155.40/x
3. Step 3: Cross multiply
   9,404.56x = 12,978.02 × 5,155.40
4. Step 4: Simplify right side
   9,404.56x = 66,906,856.64
5. Step 5: Solve for x
   x = 66,906,856.64/9,404.56
6. Step 6: Final answer
   x = 7,114.30