Finding the Fourth Proportional to 1,399.68, 1,931.46 and 810.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.68 : 1,931.46 = 810.12 : x
2. Step 2: Convert to fraction form
   1,399.68/1,931.46 = 810.12/x
3. Step 3: Cross multiply
   1,399.68x = 1,931.46 × 810.12
4. Step 4: Simplify right side
   1,399.68x = 1,564,714.38
5. Step 5: Solve for x
   x = 1,564,714.38/1,399.68
6. Step 6: Final answer
   x = 1,117.91