Finding the Fourth Proportional to 1,288.96, 1,778.89 and 816.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.96 : 1,778.89 = 816.81 : x
2. Step 2: Convert to fraction form
   1,288.96/1,778.89 = 816.81/x
3. Step 3: Cross multiply
   1,288.96x = 1,778.89 × 816.81
4. Step 4: Simplify right side
   1,288.96x = 1,453,010.67
5. Step 5: Solve for x
   x = 1,453,010.67/1,288.96
6. Step 6: Final answer
   x = 1,127.27