Finding the Fourth Proportional to 2,820.78, 3,891.96 and 1,641.60

Step by Step Solution

1. Step 1: Write the proportion equation
   2,820.78 : 3,891.96 = 1,641.60 : x
2. Step 2: Convert to fraction form
   2,820.78/3,891.96 = 1,641.60/x
3. Step 3: Cross multiply
   2,820.78x = 3,891.96 × 1,641.60
4. Step 4: Simplify right side
   2,820.78x = 6,389,041.54
5. Step 5: Solve for x
   x = 6,389,041.54/2,820.78
6. Step 6: Final answer
   x = 2,264.99