Finding the Fourth Proportional to 2,131.40, 2,939.60 and 1,291.23

Step by Step Solution

1. Step 1: Write the proportion equation
   2,131.40 : 2,939.60 = 1,291.23 : x
2. Step 2: Convert to fraction form
   2,131.40/2,939.60 = 1,291.23/x
3. Step 3: Cross multiply
   2,131.40x = 2,939.60 × 1,291.23
4. Step 4: Simplify right side
   2,131.40x = 3,795,693.25
5. Step 5: Solve for x
   x = 3,795,693.25/2,131.40
6. Step 6: Final answer
   x = 1,780.85