Finding the Fourth Proportional to 1,287.32, 1,776.56 and 789.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.32 : 1,776.56 = 789.96 : x
2. Step 2: Convert to fraction form
   1,287.32/1,776.56 = 789.96/x
3. Step 3: Cross multiply
   1,287.32x = 1,776.56 × 789.96
4. Step 4: Simplify right side
   1,287.32x = 1,403,411.34
5. Step 5: Solve for x
   x = 1,403,411.34/1,287.32
6. Step 6: Final answer
   x = 1,090.18