Finding the Fourth Proportional to 1,391.15, 1,919.99 and 801.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.15 : 1,919.99 = 801.57 : x
2. Step 2: Convert to fraction form
   1,391.15/1,919.99 = 801.57/x
3. Step 3: Cross multiply
   1,391.15x = 1,919.99 × 801.57
4. Step 4: Simplify right side
   1,391.15x = 1,539,006.38
5. Step 5: Solve for x
   x = 1,539,006.38/1,391.15
6. Step 6: Final answer
   x = 1,106.28