Finding the Fourth Proportional to 1,390.42, 1,918.59 and 800.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.42 : 1,918.59 = 800.98 : x
2. Step 2: Convert to fraction form
   1,390.42/1,918.59 = 800.98/x
3. Step 3: Cross multiply
   1,390.42x = 1,918.59 × 800.98
4. Step 4: Simplify right side
   1,390.42x = 1,536,752.22
5. Step 5: Solve for x
   x = 1,536,752.22/1,390.42
6. Step 6: Final answer
   x = 1,105.24