Finding the Fourth Proportional to 2,663.50, 3,995.90 and 839.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,663.50 : 3,995.90 = 839.50 : x
2. Step 2: Convert to fraction form
   2,663.50/3,995.90 = 839.50/x
3. Step 3: Cross multiply
   2,663.50x = 3,995.90 × 839.50
4. Step 4: Simplify right side
   2,663.50x = 3,354,558.05
5. Step 5: Solve for x
   x = 3,354,558.05/2,663.50
6. Step 6: Final answer
   x = 1,259.45