Finding the Fourth Proportional to 3,978.15, 5,969.25 and 1,639.95

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.15 : 5,969.25 = 1,639.95 : x
2. Step 2: Convert to fraction form
   3,978.15/5,969.25 = 1,639.95/x
3. Step 3: Cross multiply
   3,978.15x = 5,969.25 × 1,639.95
4. Step 4: Simplify right side
   3,978.15x = 9,789,271.54
5. Step 5: Solve for x
   x = 9,789,271.54/3,978.15
6. Step 6: Final answer
   x = 2,460.76