Finding the Fourth Proportional to 1,390.46, 1,918.91 and 801.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.46 : 1,918.91 = 801.05 : x
2. Step 2: Convert to fraction form
   1,390.46/1,918.91 = 801.05/x
3. Step 3: Cross multiply
   1,390.46x = 1,918.91 × 801.05
4. Step 4: Simplify right side
   1,390.46x = 1,537,138.85
5. Step 5: Solve for x
   x = 1,537,138.85/1,390.46
6. Step 6: Final answer
   x = 1,105.49