Finding the Fourth Proportional to 3,939.97, 5,909.85 and 978.31

Step by Step Solution

1. Step 1: Write the proportion equation
   3,939.97 : 5,909.85 = 978.31 : x
2. Step 2: Convert to fraction form
   3,939.97/5,909.85 = 978.31/x
3. Step 3: Cross multiply
   3,939.97x = 5,909.85 × 978.31
4. Step 4: Simplify right side
   3,939.97x = 5,781,665.35
5. Step 5: Solve for x
   x = 5,781,665.35/3,939.97
6. Step 6: Final answer
   x = 1,467.44