Finding the Fourth Proportional to 1,288.39, 1,777.98 and 728.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.39 : 1,777.98 = 728.91 : x
2. Step 2: Convert to fraction form
   1,288.39/1,777.98 = 728.91/x
3. Step 3: Cross multiply
   1,288.39x = 1,777.98 × 728.91
4. Step 4: Simplify right side
   1,288.39x = 1,295,979.85
5. Step 5: Solve for x
   x = 1,295,979.85/1,288.39
6. Step 6: Final answer
   x = 1,005.89