Finding the Fourth Proportional to 1,288.20, 1,777.72 and 698.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.20 : 1,777.72 = 698.73 : x
2. Step 2: Convert to fraction form
   1,288.20/1,777.72 = 698.73/x
3. Step 3: Cross multiply
   1,288.20x = 1,777.72 × 698.73
4. Step 4: Simplify right side
   1,288.20x = 1,242,146.30
5. Step 5: Solve for x
   x = 1,242,146.30/1,288.20
6. Step 6: Final answer
   x = 964.25