Finding the Fourth Proportional to 6,978.12, 9,629.79 and 3,993.88

Step by Step Solution

1. Step 1: Write the proportion equation
   6,978.12 : 9,629.79 = 3,993.88 : x
2. Step 2: Convert to fraction form
   6,978.12/9,629.79 = 3,993.88/x
3. Step 3: Cross multiply
   6,978.12x = 9,629.79 × 3,993.88
4. Step 4: Simplify right side
   6,978.12x = 38,460,225.69
5. Step 5: Solve for x
   x = 38,460,225.69/6,978.12
6. Step 6: Final answer
   x = 5,511.55