Finding the Fourth Proportional to 1,288.34, 1,777.88 and 698.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.34 : 1,777.88 = 698.87 : x
2. Step 2: Convert to fraction form
   1,288.34/1,777.88 = 698.87/x
3. Step 3: Cross multiply
   1,288.34x = 1,777.88 × 698.87
4. Step 4: Simplify right side
   1,288.34x = 1,242,499.85
5. Step 5: Solve for x
   x = 1,242,499.85/1,288.34
6. Step 6: Final answer
   x = 964.42