Finding the Fourth Proportional to 1,390.66, 1,919.11 and 801.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.66 : 1,919.11 = 801.31 : x
2. Step 2: Convert to fraction form
   1,390.66/1,919.11 = 801.31/x
3. Step 3: Cross multiply
   1,390.66x = 1,919.11 × 801.31
4. Step 4: Simplify right side
   1,390.66x = 1,537,802.03
5. Step 5: Solve for x
   x = 1,537,802.03/1,390.66
6. Step 6: Final answer
   x = 1,105.81