Finding the Fourth Proportional to 2,578.10, 3,871.69 and 1,920.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.10 : 3,871.69 = 1,920.15 : x
2. Step 2: Convert to fraction form
   2,578.10/3,871.69 = 1,920.15/x
3. Step 3: Cross multiply
   2,578.10x = 3,871.69 × 1,920.15
4. Step 4: Simplify right side
   2,578.10x = 7,434,220.75
5. Step 5: Solve for x
   x = 7,434,220.75/2,578.10
6. Step 6: Final answer
   x = 2,883.61