Finding the Fourth Proportional to 2,128.75, 3,191.67 and 1,155.53

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.75 : 3,191.67 = 1,155.53 : x
2. Step 2: Convert to fraction form
   2,128.75/3,191.67 = 1,155.53/x
3. Step 3: Cross multiply
   2,128.75x = 3,191.67 × 1,155.53
4. Step 4: Simplify right side
   2,128.75x = 3,688,078.41
5. Step 5: Solve for x
   x = 3,688,078.41/2,128.75
6. Step 6: Final answer
   x = 1,732.51