Finding the Fourth Proportional to 1,399.49, 1,931.45 and 810

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.49 : 1,931.45 = 810 : x
2. Step 2: Convert to fraction form
   1,399.49/1,931.45 = 810/x
3. Step 3: Cross multiply
   1,399.49x = 1,931.45 × 810
4. Step 4: Simplify right side
   1,399.49x = 1,564,474.50
5. Step 5: Solve for x
   x = 1,564,474.50/1,399.49
6. Step 6: Final answer
   x = 1,117.89