Finding the Fourth Proportional to 1,399.73, 1,931.47 and 810.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.73 : 1,931.47 = 810.15 : x
2. Step 2: Convert to fraction form
   1,399.73/1,931.47 = 810.15/x
3. Step 3: Cross multiply
   1,399.73x = 1,931.47 × 810.15
4. Step 4: Simplify right side
   1,399.73x = 1,564,780.42
5. Step 5: Solve for x
   x = 1,564,780.42/1,399.73
6. Step 6: Final answer
   x = 1,117.92