Finding the Fourth Proportional to 1,390.40, 1,918.96 and 800.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.40 : 1,918.96 = 800.82 : x
2. Step 2: Convert to fraction form
   1,390.40/1,918.96 = 800.82/x
3. Step 3: Cross multiply
   1,390.40x = 1,918.96 × 800.82
4. Step 4: Simplify right side
   1,390.40x = 1,536,737.54
5. Step 5: Solve for x
   x = 1,536,737.54/1,390.40
6. Step 6: Final answer
   x = 1,105.25