Finding the Fourth Proportional to 2,078.72, 3,116.90 and 691.70

Step by Step Solution

1. Step 1: Write the proportion equation
   2,078.72 : 3,116.90 = 691.70 : x
2. Step 2: Convert to fraction form
   2,078.72/3,116.90 = 691.70/x
3. Step 3: Cross multiply
   2,078.72x = 3,116.90 × 691.70
4. Step 4: Simplify right side
   2,078.72x = 2,155,959.73
5. Step 5: Solve for x
   x = 2,155,959.73/2,078.72
6. Step 6: Final answer
   x = 1,037.16