Finding the Fourth Proportional to 1,296.72, 1,789.62 and 772.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,296.72 : 1,789.62 = 772.80 : x
2. Step 2: Convert to fraction form
   1,296.72/1,789.62 = 772.80/x
3. Step 3: Cross multiply
   1,296.72x = 1,789.62 × 772.80
4. Step 4: Simplify right side
   1,296.72x = 1,383,018.34
5. Step 5: Solve for x
   x = 1,383,018.34/1,296.72
6. Step 6: Final answer
   x = 1,066.55