Finding the Fourth Proportional to 1,399.98, 1,931.84 and 810.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.98 : 1,931.84 = 810.55 : x
2. Step 2: Convert to fraction form
   1,399.98/1,931.84 = 810.55/x
3. Step 3: Cross multiply
   1,399.98x = 1,931.84 × 810.55
4. Step 4: Simplify right side
   1,399.98x = 1,565,852.91
5. Step 5: Solve for x
   x = 1,565,852.91/1,399.98
6. Step 6: Final answer
   x = 1,118.49