Finding the Fourth Proportional to 1,247.94, 1,721.86 and 805.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,247.94 : 1,721.86 = 805.76 : x
2. Step 2: Convert to fraction form
   1,247.94/1,721.86 = 805.76/x
3. Step 3: Cross multiply
   1,247.94x = 1,721.86 × 805.76
4. Step 4: Simplify right side
   1,247.94x = 1,387,411.43
5. Step 5: Solve for x
   x = 1,387,411.43/1,247.94
6. Step 6: Final answer
   x = 1,111.76