Finding the Fourth Proportional to 2,140.78, 3,210.76 and 679.94

Step by Step Solution

1. Step 1: Write the proportion equation
   2,140.78 : 3,210.76 = 679.94 : x
2. Step 2: Convert to fraction form
   2,140.78/3,210.76 = 679.94/x
3. Step 3: Cross multiply
   2,140.78x = 3,210.76 × 679.94
4. Step 4: Simplify right side
   2,140.78x = 2,183,124.15
5. Step 5: Solve for x
   x = 2,183,124.15/2,140.78
6. Step 6: Final answer
   x = 1,019.78