Finding the Fourth Proportional to 1,007.80, 1,389.86 and 727.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.80 : 1,389.86 = 727.88 : x
2. Step 2: Convert to fraction form
   1,007.80/1,389.86 = 727.88/x
3. Step 3: Cross multiply
   1,007.80x = 1,389.86 × 727.88
4. Step 4: Simplify right side
   1,007.80x = 1,011,651.30
5. Step 5: Solve for x
   x = 1,011,651.30/1,007.80
6. Step 6: Final answer
   x = 1,003.82