Finding the Fourth Proportional to 2,143.90, 3,216.15 and 911.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,143.90 : 3,216.15 = 911.30 : x
2. Step 2: Convert to fraction form
   2,143.90/3,216.15 = 911.30/x
3. Step 3: Cross multiply
   2,143.90x = 3,216.15 × 911.30
4. Step 4: Simplify right side
   2,143.90x = 2,930,877.50
5. Step 5: Solve for x
   x = 2,930,877.50/2,143.90
6. Step 6: Final answer
   x = 1,367.08