Finding the Fourth Proportional to 1,391.10, 1,919.82 and 801.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.10 : 1,919.82 = 801.72 : x
2. Step 2: Convert to fraction form
   1,391.10/1,919.82 = 801.72/x
3. Step 3: Cross multiply
   1,391.10x = 1,919.82 × 801.72
4. Step 4: Simplify right side
   1,391.10x = 1,539,158.09
5. Step 5: Solve for x
   x = 1,539,158.09/1,391.10
6. Step 6: Final answer
   x = 1,106.43