Finding the Fourth Proportional to 1,390.30, 1,918.82 and 800.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.30 : 1,918.82 = 800.74 : x
2. Step 2: Convert to fraction form
   1,390.30/1,918.82 = 800.74/x
3. Step 3: Cross multiply
   1,390.30x = 1,918.82 × 800.74
4. Step 4: Simplify right side
   1,390.30x = 1,536,475.93
5. Step 5: Solve for x
   x = 1,536,475.93/1,390.30
6. Step 6: Final answer
   x = 1,105.14