Finding the Fourth Proportional to 1,581.57, 2,182.89 and 991.68

Step by Step Solution

1. Step 1: Write the proportion equation
   1,581.57 : 2,182.89 = 991.68 : x
2. Step 2: Convert to fraction form
   1,581.57/2,182.89 = 991.68/x
3. Step 3: Cross multiply
   1,581.57x = 2,182.89 × 991.68
4. Step 4: Simplify right side
   1,581.57x = 2,164,728.36
5. Step 5: Solve for x
   x = 2,164,728.36/1,581.57
6. Step 6: Final answer
   x = 1,368.72