Finding the Fourth Proportional to 2,139.78, 3,196.07 and 1,678.08

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.78 : 3,196.07 = 1,678.08 : x
2. Step 2: Convert to fraction form
   2,139.78/3,196.07 = 1,678.08/x
3. Step 3: Cross multiply
   2,139.78x = 3,196.07 × 1,678.08
4. Step 4: Simplify right side
   2,139.78x = 5,363,261.15
5. Step 5: Solve for x
   x = 5,363,261.15/2,139.78
6. Step 6: Final answer
   x = 2,506.45