Finding the Fourth Proportional to 1,211.88, 1,672.41 and 687.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,211.88 : 1,672.41 = 687.81 : x
2. Step 2: Convert to fraction form
   1,211.88/1,672.41 = 687.81/x
3. Step 3: Cross multiply
   1,211.88x = 1,672.41 × 687.81
4. Step 4: Simplify right side
   1,211.88x = 1,150,300.32
5. Step 5: Solve for x
   x = 1,150,300.32/1,211.88
6. Step 6: Final answer
   x = 949.19