Finding the Fourth Proportional to 2,139.40, 2,951.82 and 1,990.75

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.40 : 2,951.82 = 1,990.75 : x
2. Step 2: Convert to fraction form
   2,139.40/2,951.82 = 1,990.75/x
3. Step 3: Cross multiply
   2,139.40x = 2,951.82 × 1,990.75
4. Step 4: Simplify right side
   2,139.40x = 5,876,335.67
5. Step 5: Solve for x
   x = 5,876,335.67/2,139.40
6. Step 6: Final answer
   x = 2,746.72