Finding the Fourth Proportional to 1,978.21, 2,966.46 and 679.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.21 : 2,966.46 = 679.78 : x
2. Step 2: Convert to fraction form
   1,978.21/2,966.46 = 679.78/x
3. Step 3: Cross multiply
   1,978.21x = 2,966.46 × 679.78
4. Step 4: Simplify right side
   1,978.21x = 2,016,540.18
5. Step 5: Solve for x
   x = 2,016,540.18/1,978.21
6. Step 6: Final answer
   x = 1,019.38