Finding the Fourth Proportional to 1,287.62, 1,776.83 and 728.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.62 : 1,776.83 = 728.12 : x
2. Step 2: Convert to fraction form
   1,287.62/1,776.83 = 728.12/x
3. Step 3: Cross multiply
   1,287.62x = 1,776.83 × 728.12
4. Step 4: Simplify right side
   1,287.62x = 1,293,745.46
5. Step 5: Solve for x
   x = 1,293,745.46/1,287.62
6. Step 6: Final answer
   x = 1,004.76