Finding the Fourth Proportional to 1,272.72, 1,912.28 and 810.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,272.72 : 1,912.28 = 810.71 : x
2. Step 2: Convert to fraction form
   1,272.72/1,912.28 = 810.71/x
3. Step 3: Cross multiply
   1,272.72x = 1,912.28 × 810.71
4. Step 4: Simplify right side
   1,272.72x = 1,550,290.90
5. Step 5: Solve for x
   x = 1,550,290.90/1,272.72
6. Step 6: Final answer
   x = 1,218.09