Finding the Fourth Proportional to 1,287.57, 1,776.27 and 790.03

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.57 : 1,776.27 = 790.03 : x
2. Step 2: Convert to fraction form
   1,287.57/1,776.27 = 790.03/x
3. Step 3: Cross multiply
   1,287.57x = 1,776.27 × 790.03
4. Step 4: Simplify right side
   1,287.57x = 1,403,306.59
5. Step 5: Solve for x
   x = 1,403,306.59/1,287.57
6. Step 6: Final answer
   x = 1,089.89