Finding the Fourth Proportional to 3,979.89, 5,491.91 and 2,187.31

Step by Step Solution

1. Step 1: Write the proportion equation
   3,979.89 : 5,491.91 = 2,187.31 : x
2. Step 2: Convert to fraction form
   3,979.89/5,491.91 = 2,187.31/x
3. Step 3: Cross multiply
   3,979.89x = 5,491.91 × 2,187.31
4. Step 4: Simplify right side
   3,979.89x = 12,012,509.66
5. Step 5: Solve for x
   x = 12,012,509.66/3,979.89
6. Step 6: Final answer
   x = 3,018.30