Finding the Fourth Proportional to 1,399.61, 1,931.31 and 810.02

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.61 : 1,931.31 = 810.02 : x
2. Step 2: Convert to fraction form
   1,399.61/1,931.31 = 810.02/x
3. Step 3: Cross multiply
   1,399.61x = 1,931.31 × 810.02
4. Step 4: Simplify right side
   1,399.61x = 1,564,390.07
5. Step 5: Solve for x
   x = 1,564,390.07/1,399.61
6. Step 6: Final answer
   x = 1,117.74