Finding the Fourth Proportional to 1,288.58, 1,778.22 and 699.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.58 : 1,778.22 = 699.12 : x
2. Step 2: Convert to fraction form
   1,288.58/1,778.22 = 699.12/x
3. Step 3: Cross multiply
   1,288.58x = 1,778.22 × 699.12
4. Step 4: Simplify right side
   1,288.58x = 1,243,189.17
5. Step 5: Solve for x
   x = 1,243,189.17/1,288.58
6. Step 6: Final answer
   x = 964.78