Finding the Fourth Proportional to 1,288.17, 1,777.61 and 698.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.17 : 1,777.61 = 698.69 : x
2. Step 2: Convert to fraction form
   1,288.17/1,777.61 = 698.69/x
3. Step 3: Cross multiply
   1,288.17x = 1,777.61 × 698.69
4. Step 4: Simplify right side
   1,288.17x = 1,241,985.95
5. Step 5: Solve for x
   x = 1,241,985.95/1,288.17
6. Step 6: Final answer
   x = 964.15