Finding the Fourth Proportional to 1,491.10, 2,057.67 and 861.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,491.10 : 2,057.67 = 861.57 : x
2. Step 2: Convert to fraction form
   1,491.10/2,057.67 = 861.57/x
3. Step 3: Cross multiply
   1,491.10x = 2,057.67 × 861.57
4. Step 4: Simplify right side
   1,491.10x = 1,772,826.74
5. Step 5: Solve for x
   x = 1,772,826.74/1,491.10
6. Step 6: Final answer
   x = 1,188.94