Finding the Fourth Proportional to 3,978.18, 5,969.32 and 1,639.91

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978.18 : 5,969.32 = 1,639.91 : x
2. Step 2: Convert to fraction form
   3,978.18/5,969.32 = 1,639.91/x
3. Step 3: Cross multiply
   3,978.18x = 5,969.32 × 1,639.91
4. Step 4: Simplify right side
   3,978.18x = 9,789,147.56
5. Step 5: Solve for x
   x = 9,789,147.56/3,978.18
6. Step 6: Final answer
   x = 2,460.71