Finding the Fourth Proportional to 1,390.68, 1,919.10 and 801.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.68 : 1,919.10 = 801.30 : x
2. Step 2: Convert to fraction form
   1,390.68/1,919.10 = 801.30/x
3. Step 3: Cross multiply
   1,390.68x = 1,919.10 × 801.30
4. Step 4: Simplify right side
   1,390.68x = 1,537,774.83
5. Step 5: Solve for x
   x = 1,537,774.83/1,390.68
6. Step 6: Final answer
   x = 1,105.77