Finding the Fourth Proportional to 1,222.88, 1,687.57 and 698.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.88 : 1,687.57 = 698.91 : x
2. Step 2: Convert to fraction form
   1,222.88/1,687.57 = 698.91/x
3. Step 3: Cross multiply
   1,222.88x = 1,687.57 × 698.91
4. Step 4: Simplify right side
   1,222.88x = 1,179,459.55
5. Step 5: Solve for x
   x = 1,179,459.55/1,222.88
6. Step 6: Final answer
   x = 964.49