Finding the Fourth Proportional to 2,121.78, 3,181.49 and 1,685.82

Step by Step Solution

1. Step 1: Write the proportion equation
   2,121.78 : 3,181.49 = 1,685.82 : x
2. Step 2: Convert to fraction form
   2,121.78/3,181.49 = 1,685.82/x
3. Step 3: Cross multiply
   2,121.78x = 3,181.49 × 1,685.82
4. Step 4: Simplify right side
   2,121.78x = 5,363,411.04
5. Step 5: Solve for x
   x = 5,363,411.04/2,121.78
6. Step 6: Final answer
   x = 2,527.79