Finding the Fourth Proportional to 2,081.20, 2,870.72 and 1,638.92

Step by Step Solution

1. Step 1: Write the proportion equation
   2,081.20 : 2,870.72 = 1,638.92 : x
2. Step 2: Convert to fraction form
   2,081.20/2,870.72 = 1,638.92/x
3. Step 3: Cross multiply
   2,081.20x = 2,870.72 × 1,638.92
4. Step 4: Simplify right side
   2,081.20x = 4,704,880.42
5. Step 5: Solve for x
   x = 4,704,880.42/2,081.20
6. Step 6: Final answer
   x = 2,260.66