Finding the Fourth Proportional to 1,222.51, 1,687.35 and 781.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.51 : 1,687.35 = 781.06 : x
2. Step 2: Convert to fraction form
   1,222.51/1,687.35 = 781.06/x
3. Step 3: Cross multiply
   1,222.51x = 1,687.35 × 781.06
4. Step 4: Simplify right side
   1,222.51x = 1,317,921.59
5. Step 5: Solve for x
   x = 1,317,921.59/1,222.51
6. Step 6: Final answer
   x = 1,078.05