Finding the Fourth Proportional to 3,909.89, 5,861.18 and 1,311

Step by Step Solution

1. Step 1: Write the proportion equation
   3,909.89 : 5,861.18 = 1,311 : x
2. Step 2: Convert to fraction form
   3,909.89/5,861.18 = 1,311/x
3. Step 3: Cross multiply
   3,909.89x = 5,861.18 × 1,311
4. Step 4: Simplify right side
   3,909.89x = 7,684,010.26
5. Step 5: Solve for x
   x = 7,684,010.26/3,909.89
6. Step 6: Final answer
   x = 1,965.28