Finding the Fourth Proportional to 8,662.68, 12,978.38 and 3,986.60

Step by Step Solution

1. Step 1: Write the proportion equation
   8,662.68 : 12,978.38 = 3,986.60 : x
2. Step 2: Convert to fraction form
   8,662.68/12,978.38 = 3,986.60/x
3. Step 3: Cross multiply
   8,662.68x = 12,978.38 × 3,986.60
4. Step 4: Simplify right side
   8,662.68x = 51,739,605.36
5. Step 5: Solve for x
   x = 51,739,605.36/8,662.68
6. Step 6: Final answer
   x = 5,972.70