Finding the Fourth Proportional to 2,139.40, 3,209.41 and 969.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.40 : 3,209.41 = 969.80 : x
2. Step 2: Convert to fraction form
   2,139.40/3,209.41 = 969.80/x
3. Step 3: Cross multiply
   2,139.40x = 3,209.41 × 969.80
4. Step 4: Simplify right side
   2,139.40x = 3,112,485.82
5. Step 5: Solve for x
   x = 3,112,485.82/2,139.40
6. Step 6: Final answer
   x = 1,454.84