Finding the Fourth Proportional to 2,185.60, 3,279.84 and 1,638.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,185.60 : 3,279.84 = 1,638.40 : x
2. Step 2: Convert to fraction form
   2,185.60/3,279.84 = 1,638.40/x
3. Step 3: Cross multiply
   2,185.60x = 3,279.84 × 1,638.40
4. Step 4: Simplify right side
   2,185.60x = 5,373,689.86
5. Step 5: Solve for x
   x = 5,373,689.86/2,185.60
6. Step 6: Final answer
   x = 2,458.68